contrib: Use text=True in subprocess over manual encoding handling

diff --git a/contrib/devtools/copyright_header.py b/contrib/devtools/copyright_header.py
index 0d9f3543..aa77de8a 100755
--- a/contrib/devtools/copyright_header.py
+++ b/contrib/devtools/copyright_header.py
@@ -54,12 +54,12 @@ GIT_LS_CMD = 'git ls-files --full-name'.split(' ')
 GIT_TOPLEVEL_CMD = 'git rev-parse --show-toplevel'.split(' ')
 
 def call_git_ls(base_directory):
-    out = subprocess.check_output([*GIT_LS_CMD, base_directory])
-    return [f for f in out.decode("utf-8").split('\n') if f != '']
+    out = subprocess.check_output([*GIT_LS_CMD, base_directory], text=True)
+    return [f for f in out.split('\n') if f != '']
 
 def call_git_toplevel():
     "Returns the absolute path to the project root"
-    return subprocess.check_output(GIT_TOPLEVEL_CMD).strip().decode("utf-8")
+    return subprocess.check_output(GIT_TOPLEVEL_CMD, text=True).strip()
 
 def get_filenames_to_examine(base_directory):
     "Returns an array of absolute paths to any project files in the base_directory that pass the include/exclude filters"
@@ -298,8 +298,8 @@ def report_cmd(argv):
 GIT_LOG_CMD = "git log --pretty=format:%%ai %s"
 
 def call_git_log(filename):
-    out = subprocess.check_output((GIT_LOG_CMD % filename).split(' '))
-    return out.decode("utf-8").split('\n')
+    out = subprocess.check_output((GIT_LOG_CMD % filename).split(' '), text=True)
+    return out.split('\n')
 
 def get_git_change_years(filename):
     git_log_lines = call_git_log(filename)
diff --git a/contrib/verify-commits/verify-commits.py b/contrib/verify-commits/verify-commits.py
index b5c028cf..1af6b031 100755
--- a/contrib/verify-commits/verify-commits.py
+++ b/contrib/verify-commits/verify-commits.py
@@ -140,8 +140,8 @@ def main():
 
         # Check that the commit (and parents) was signed with a trusted key
         valid_sig = False
-        verify_res = subprocess.run([GIT, '-c', 'gpg.program={}/gpg.sh'.format(dirname), 'verify-commit', "--raw", current_commit], capture_output=True)
-        for line in verify_res.stderr.decode().splitlines():
+        verify_res = subprocess.run([GIT, '-c', 'gpg.program={}/gpg.sh'.format(dirname), 'verify-commit', "--raw", current_commit], text=True, capture_output=True)
+        for line in verify_res.stderr.splitlines():
             if line.startswith("[GNUPG:] VALIDSIG "):
                 key = line.split(" ")[-1]
                 valid_sig = key in trusted_keys
@@ -152,7 +152,7 @@ def main():
             if prev_commit != "":
                 print("No parent of {} was signed with a trusted key!".format(prev_commit), file=sys.stderr)
                 print("Parents are:", file=sys.stderr)
-                parents = subprocess.check_output([GIT, 'show', '-s', '--format=format:%P', prev_commit]).decode('utf8').splitlines()[0].split(' ')
+                parents = subprocess.check_output([GIT, 'show', '-s', '--format=format:%P', prev_commit], text=True).splitlines()[0].split(' ')
                 for parent in parents:
                     subprocess.call([GIT, 'show', '-s', parent], stdout=sys.stderr)
             else:
@@ -162,29 +162,29 @@ def main():
         # Check the Tree-SHA512
         if (verify_tree or prev_commit == "") and current_commit not in incorrect_sha512_allowed:
             tree_hash = tree_sha512sum(current_commit)
-            if ("Tree-SHA512: {}".format(tree_hash)) not in subprocess.check_output([GIT, 'show', '-s', '--format=format:%B', current_commit]).decode('utf8').splitlines():
+            if ("Tree-SHA512: {}".format(tree_hash)) not in subprocess.check_output([GIT, 'show', '-s', '--format=format:%B', current_commit], text=True).splitlines():
                 print("Tree-SHA512 did not match for commit " + current_commit, file=sys.stderr)
                 sys.exit(1)
 
         # Merge commits should only have two parents
-        parents = subprocess.check_output([GIT, 'show', '-s', '--format=format:%P', current_commit]).decode('utf8').splitlines()[0].split(' ')
+        parents = subprocess.check_output([GIT, 'show', '-s', '--format=format:%P', current_commit], text=True).splitlines()[0].split(' ')
         if len(parents) > 2:
             print("Commit {} is an octopus merge".format(current_commit), file=sys.stderr)
             sys.exit(1)
 
         # Check that the merge commit is clean
-        commit_time = int(subprocess.check_output([GIT, 'show', '-s', '--format=format:%ct', current_commit]).decode('utf8').splitlines()[0])
+        commit_time = int(subprocess.check_output([GIT, 'show', '-s', '--format=format:%ct', current_commit], text=True).splitlines()[0])
         check_merge = commit_time > time.time() - args.clean_merge * 24 * 60 * 60  # Only check commits in clean_merge days
         allow_unclean = current_commit in unclean_merge_allowed
         if len(parents) == 2 and check_merge and not allow_unclean:
-            current_tree = subprocess.check_output([GIT, 'show', '--format=%T', current_commit]).decode('utf8').splitlines()[0]
+            current_tree = subprocess.check_output([GIT, 'show', '--format=%T', current_commit], text=True).splitlines()[0]
 
             # This merge-tree functionality requires git >= 2.38. The
             # --write-tree option was added in order to opt-in to the new
             # behavior. Older versions of git will not recognize the option and
             # will instead exit with code 128.
             try:
-                recreated_tree = subprocess.check_output([GIT, "merge-tree", "--write-tree", parents[0], parents[1]]).decode('utf8').splitlines()[0]
+                recreated_tree = subprocess.check_output([GIT, "merge-tree", "--write-tree", parents[0], parents[1]], text=True).splitlines()[0]
             except subprocess.CalledProcessError as e:
                 if e.returncode == 128:
                     print("git v2.38+ is required for this functionality.", file=sys.stderr)
diff --git a/test/functional/feature_framework_startup_failures.py b/test/functional/feature_framework_startup_failures.py
index 84a7d9d8..43dbeae7 100755
--- a/test/functional/feature_framework_startup_failures.py
+++ b/test/functional/feature_framework_startup_failures.py
@@ -43,15 +43,13 @@ class FeatureFrameworkStartupFailures(BitcoinTestFramework):
         args = [sys.executable] + sys.argv + [f"--tmpdir={self.options.tmpdir}/{subdir}", f"--internal_test={test.__name__}"] + internal_args
 
         try:
-            # The subprocess encoding argument gives different results for e.output
-            # on Linux/Windows, so handle decoding by ourselves for consistency.
             output = subprocess.run(args, timeout=60 * self.options.timeout_factor,
-                                    stdout=subprocess.PIPE, stderr=subprocess.STDOUT).stdout.decode("utf-8")
+                                    stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True).stdout
         except subprocess.TimeoutExpired as e:
             print("Unexpected child process timeout!\n"
                   "WARNING: Timeouts like this halt execution of TestNode logic, "
                   "meaning dangling bitcoind processes are to be expected.\n"
-                  f"<CHILD OUTPUT BEGIN>\n{e.output.decode('utf-8')}\n<CHILD OUTPUT END>",
+                  f"<CHILD OUTPUT BEGIN>\n{e.output}\n<CHILD OUTPUT END>",
                   file=sys.stderr)
             raise
 
diff --git a/test/functional/tool_signet_miner.py b/test/functional/tool_signet_miner.py
index dbf64b64..2be47332 100755
--- a/test/functional/tool_signet_miner.py
+++ b/test/functional/tool_signet_miner.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright (c) 2022 The Bitcoin Core developers
+# Copyright (c) 2022-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test signet miner tool"""
@@ -102,8 +102,8 @@ class SignetMinerTest(BitcoinTestFramework):
                 'genpsbt',
                 f'--address={node.getnewaddress()}',
                 '--poolnum=98',
-            ], check=True, input=json.dumps(template).encode('utf8'), capture_output=True)
-        psbt = genpsbt.stdout.decode('utf8').strip()
+            ], check=True, text=True, input=json.dumps(template), capture_output=True)
+        psbt = genpsbt.stdout.strip()
         if sign:
             self.log.debug("Sign the PSBT")
             res = node.walletprocesspsbt(psbt=psbt, sign=True, sighashtype='ALL')
@@ -112,8 +112,8 @@ class SignetMinerTest(BitcoinTestFramework):
         solvepsbt = subprocess.run(base_cmd + [
                 'solvepsbt',
                 f'--grind-cmd={shlex.join(util_argv)}',
-            ], check=True, input=psbt.encode('utf8'), capture_output=True)
-        node.submitblock(solvepsbt.stdout.decode('utf8').strip())
+            ], check=True, text=True, input=psbt, capture_output=True)
+        node.submitblock(solvepsbt.stdout.strip())
         assert_equal(node.getblockcount(), n_blocks + 1)
 
     def run_test(self):
diff --git a/test/lint/check-doc.py b/test/lint/check-doc.py
index e47ff30f..4dc605b1 100755
--- a/test/lint/check-doc.py
+++ b/test/lint/check-doc.py
@@ -1,13 +1,11 @@
 #!/usr/bin/env python3
-# Copyright (c) 2015-2022 The Bitcoin Core developers
+# Copyright (c) 2015-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 '''
 This checks if all command line args are documented.
 Return value is 0 to indicate no error.
-
-Author: @MarcoFalke
 '''
 
 from subprocess import check_output
@@ -27,8 +25,8 @@ SET_DOC_OPTIONAL = set(['-h', '-?', '-dbcrashratio', '-forcecompactdb', '-ipccon
 
 
 def lint_missing_argument_documentation():
-    used = check_output(CMD_GREP_ARGS, shell=True).decode('utf8').strip()
-    docd = check_output(CMD_GREP_DOCS, shell=True).decode('utf8').strip()
+    used = check_output(CMD_GREP_ARGS, shell=True, text=True).strip()
+    docd = check_output(CMD_GREP_DOCS, shell=True, text=True).strip()
 
     args_used = set(re.findall(re.compile(REGEX_ARG), used))
     args_docd = set(re.findall(re.compile(REGEX_DOC), docd)).union(SET_DOC_OPTIONAL)
@@ -46,8 +44,8 @@ def lint_missing_argument_documentation():
 
 
 def lint_missing_hidden_wallet_args():
-    wallet_args = check_output(CMD_GREP_WALLET_ARGS, shell=True).decode('utf8').strip()
-    wallet_hidden_args = check_output(CMD_GREP_WALLET_HIDDEN_ARGS, shell=True).decode('utf8').strip()
+    wallet_args = check_output(CMD_GREP_WALLET_ARGS, shell=True, text=True).strip()
+    wallet_hidden_args = check_output(CMD_GREP_WALLET_HIDDEN_ARGS, shell=True, text=True).strip()
 
     wallet_args = set(re.findall(re.compile(REGEX_DOC), wallet_args))
     wallet_hidden_args = set(re.findall(re.compile(r'    "([^"=]+)'), wallet_hidden_args))
diff --git a/test/lint/lint-files.py b/test/lint/lint-files.py
index b510830d..6d9d7d27 100755
--- a/test/lint/lint-files.py
+++ b/test/lint/lint-files.py
@@ -76,7 +76,7 @@ def get_git_file_metadata() -> dict[str, FileMeta]:
     '''
     Return a dictionary mapping the name of all files in the repository to git tree metadata.
     '''
-    files_raw = check_output(CMD_ALL_FILES).decode("utf8").rstrip("\0").split("\0")
+    files_raw = check_output(CMD_ALL_FILES, text=True).rstrip("\0").split("\0")
     files = {}
     for file_spec in files_raw:
         meta = FileMeta(file_spec)
@@ -169,7 +169,7 @@ def check_shebang_file_permissions(files_meta) -> int:
     """
     Checks every file that contains a shebang line to ensure it has an executable permission
     """
-    filenames = check_output(CMD_SHEBANG_FILES).decode("utf8").strip().split("\n")
+    filenames = check_output(CMD_SHEBANG_FILES, text=True).strip().split("\n")
 
     # The git grep command we use returns files which contain a shebang on any line within the file
     # so we need to filter the list to only files with the shebang on the first line
@@ -198,7 +198,7 @@ def check_shebang_file_permissions(files_meta) -> int:
 
 
 def main() -> NoReturn:
-    root_dir = check_output(CMD_TOP_LEVEL).decode("utf8").strip()
+    root_dir = check_output(CMD_TOP_LEVEL, text=True).strip()
     os.chdir(root_dir)
 
     files = get_git_file_metadata()
diff --git a/test/lint/lint-include-guards.py b/test/lint/lint-include-guards.py
index c56eeab3..dbbf0325 100755
--- a/test/lint/lint-include-guards.py
+++ b/test/lint/lint-include-guards.py
@@ -31,7 +31,7 @@ def _get_header_file_lst() -> list[str]:
     """
     git_cmd_lst = ['git', 'ls-files', '--', '*.h']
     header_file_lst = check_output(
-        git_cmd_lst).decode('utf-8').splitlines()
+        git_cmd_lst, text=True).splitlines()
 
     header_file_lst = [hf for hf in header_file_lst
                        if not any(ef in hf for ef
diff --git a/test/lint/lint-python-dead-code.py b/test/lint/lint-python-dead-code.py
index b3f93947..cd6471e2 100755
--- a/test/lint/lint-python-dead-code.py
+++ b/test/lint/lint-python-dead-code.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (c) 2022 The Bitcoin Core developers
+# Copyright (c) 2022-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -24,15 +24,15 @@ def check_vulture_install():
 def main():
     check_vulture_install()
 
-    files = check_output(FILES_ARGS).decode("utf-8").splitlines()
+    files = check_output(FILES_ARGS, text=True).splitlines()
     # --min-confidence 100 will only report code that is guaranteed to be unused within the analyzed files.
     # Any value below 100 introduces the risk of false positives, which would create an unacceptable maintenance burden.
     vulture_args = ['vulture', '--min-confidence=100'] + files
 
     try:
-        check_output(vulture_args, stderr=STDOUT)
+        check_output(vulture_args, stderr=STDOUT, text=True)
     except CalledProcessError as e:
-        print(e.output.decode("utf-8"), end="")
+        print(e.output, end="")
         print("Python dead code detection found some issues")
         exit(1)
 
diff --git a/test/lint/lint-python.py b/test/lint/lint-python.py
index e2dbe25b..fd1a8495 100755
--- a/test/lint/lint-python.py
+++ b/test/lint/lint-python.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (c) 2022 The Bitcoin Core developers
+# Copyright (c) 2022-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -37,7 +37,7 @@ def check_dependencies():
 def main():
     check_dependencies()
 
-    mypy_files = subprocess.check_output(MYPY_FILES_ARGS).decode("utf-8").splitlines()
+    mypy_files = subprocess.check_output(MYPY_FILES_ARGS, text=True).splitlines()
     mypy_args = ['mypy', '--show-error-codes'] + mypy_files
 
     try:
diff --git a/test/lint/lint-shell-locale.py b/test/lint/lint-shell-locale.py
index 3602289d..80b1d4d0 100755
--- a/test/lint/lint-shell-locale.py
+++ b/test/lint/lint-shell-locale.py
@@ -27,10 +27,10 @@ def get_shell_files_list():
         '*.sh',
     ]
     try:
-        return subprocess.check_output(command, stderr = subprocess.STDOUT).decode('utf-8').splitlines()
+        return subprocess.check_output(command, stderr = subprocess.STDOUT, text=True).splitlines()
     except subprocess.CalledProcessError as e:
         if e.returncode > 1: # return code is 1 when match is empty
-            print(e.output.decode('utf-8'), end='')
+            print(e.output, end='')
             sys.exit(1)
         return []
 
diff --git a/test/lint/lint-spelling.py b/test/lint/lint-spelling.py
index 945288a3..cd34162c 100755
--- a/test/lint/lint-spelling.py
+++ b/test/lint/lint-spelling.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (c) 2022 The Bitcoin Core developers
+# Copyright (c) 2022-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -29,13 +29,13 @@ def check_codespell_install():
 def main():
     check_codespell_install()
 
-    files = check_output(FILES_ARGS).decode("utf-8").splitlines()
+    files = check_output(FILES_ARGS, text=True).splitlines()
     codespell_args = ['codespell', '--check-filenames', '--disable-colors', '--quiet-level=7', '--ignore-words={}'.format(IGNORE_WORDS_FILE)] + files
 
     try:
-        check_output(codespell_args, stderr=STDOUT)
+        check_output(codespell_args, stderr=STDOUT, text=True)
     except CalledProcessError as e:
-        print(e.output.decode("utf-8"), end="")
+        print(e.output, end="")
         print('^ Warning: codespell identified likely spelling errors. Any false positives? Add them to the list of ignored words in {}'.format(IGNORE_WORDS_FILE))
 
 
diff --git a/test/lint/lint-submodule.py b/test/lint/lint-submodule.py
index 4d2fbf08..d5700d33 100755
--- a/test/lint/lint-submodule.py
+++ b/test/lint/lint-submodule.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (c) 2022 The Bitcoin Core developers
+# Copyright (c) 2022-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -13,7 +13,7 @@ import sys
 
 def main():
     submodules_list = subprocess.check_output(['git', 'submodule', 'status', '--recursive'],
-                                                text = True, encoding = 'utf8').rstrip('\n')
+                                                text = True).rstrip('\n')
     if submodules_list:
         print("These submodules were found, delete them:\n", submodules_list)
         sys.exit(1)