wallet: mark `bip125-replaceable` key as deprecated in transaction RPCs

diff --git a/src/wallet/rpc/transactions.cpp b/src/wallet/rpc/transactions.cpp
index 038e30fc..f69082e1 100644
--- a/src/wallet/rpc/transactions.cpp
+++ b/src/wallet/rpc/transactions.cpp
@@ -50,15 +50,17 @@ static void WalletTxToJSON(const CWallet& wallet, const CWalletTx& wtx, UniValue
     entry.pushKV("timereceived", wtx.nTimeReceived);
 
     // Add opt-in RBF status
-    std::string rbfStatus = "no";
-    if (confirms <= 0) {
-        RBFTransactionState rbfState = chain.isRBFOptIn(*wtx.tx);
-        if (rbfState == RBFTransactionState::UNKNOWN)
-            rbfStatus = "unknown";
-        else if (rbfState == RBFTransactionState::REPLACEABLE_BIP125)
-            rbfStatus = "yes";
+    if (chain.rpcEnableDeprecated("bip125")) {
+        std::string rbfStatus = "no";
+        if (confirms <= 0) {
+            RBFTransactionState rbfState = chain.isRBFOptIn(*wtx.tx);
+            if (rbfState == RBFTransactionState::UNKNOWN)
+                rbfStatus = "unknown";
+            else if (rbfState == RBFTransactionState::REPLACEABLE_BIP125)
+                rbfStatus = "yes";
+        }
+        entry.pushKV("bip125-replaceable", rbfStatus);
     }
-    entry.pushKV("bip125-replaceable", rbfStatus);
 
     for (const std::pair<const std::string, std::string>& item : wtx.mapValue)
         entry.pushKV(item.first, item.second);
@@ -405,7 +407,7 @@ static std::vector<RPCResult> TransactionDescriptionString()
            {RPCResult::Type::NUM_TIME, "time", "The transaction time expressed in " + UNIX_EPOCH_TIME + "."},
            {RPCResult::Type::NUM_TIME, "timereceived", "The time received expressed in " + UNIX_EPOCH_TIME + "."},
            {RPCResult::Type::STR, "comment", /*optional=*/true, "If a comment is associated with the transaction, only present if not empty."},
-           {RPCResult::Type::STR, "bip125-replaceable", "(\"yes|no|unknown\") Whether this transaction signals BIP125 replaceability or has an unconfirmed ancestor signaling BIP125 replaceability.\n"
+           {RPCResult::Type::STR, "bip125-replaceable", /*optional=*/true, "(\"yes|no|unknown\") (DEPRECATED) Whether this transaction signals BIP125 replaceability or has an unconfirmed ancestor signaling BIP125 replaceability.\n"
                "May be unknown for unconfirmed transactions not in the mempool because their unconfirmed ancestors are unknown."},
            {RPCResult::Type::ARR, "parent_descs", /*optional=*/true, "Only if 'category' is 'received'. List of parent descriptors for the output script of this coin.", {
                {RPCResult::Type::STR, "desc", "The descriptor string."},
diff --git a/test/functional/wallet_basic.py b/test/functional/wallet_basic.py
index e7a333ba..11f27ed7 100755
--- a/test/functional/wallet_basic.py
+++ b/test/functional/wallet_basic.py
@@ -510,7 +510,7 @@ class WalletTest(BitcoinTestFramework):
         # Try with walletrejectlongchains
         # Double chain limit but require combining inputs, so we pass AttemptSelection
         self.stop_node(0)
-        extra_args = ["-walletrejectlongchains", "-limitclustercount=" + str(2 * chainlimit), "-limitancestorcount=" + str(2*chainlimit)]
+        extra_args = ["-deprecatedrpc=bip125", "-walletrejectlongchains", "-limitclustercount=" + str(2 * chainlimit), "-limitancestorcount=" + str(2*chainlimit)]
         self.start_node(0, extra_args=extra_args)
 
         # wait until the wallet has submitted all transactions to the mempool
diff --git a/test/functional/wallet_listtransactions.py b/test/functional/wallet_listtransactions.py
index 714e6594..93e8a45b 100755
--- a/test/functional/wallet_listtransactions.py
+++ b/test/functional/wallet_listtransactions.py
@@ -31,7 +31,7 @@ class ListTransactionsTest(BitcoinTestFramework):
         self.num_nodes = 3
         # whitelist peers to speed up tx relay / mempool sync
         self.noban_tx_relay = True
-        self.extra_args = [["-walletrbf=0"]] * self.num_nodes
+        self.extra_args = [["-walletrbf=0", "-deprecatedrpc=bip125"]] * self.num_nodes
 
     def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()
diff --git a/test/functional/wallet_migration.py b/test/functional/wallet_migration.py
index e28cfd57..42b2a47b 100755
--- a/test/functional/wallet_migration.py
+++ b/test/functional/wallet_migration.py
@@ -44,7 +44,7 @@ class WalletMigrationTest(BitcoinTestFramework):
         self.setup_clean_chain = True
         self.num_nodes = 2
         self.supports_cli = False
-        self.extra_args = [[], ["-deprecatedrpc=create_bdb"]]
+        self.extra_args = [["-deprecatedrpc=bip125"], ["-deprecatedrpc=create_bdb"]]
 
     def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()
diff --git a/test/functional/wallet_send.py b/test/functional/wallet_send.py
index ba986990..5011deea 100755
--- a/test/functional/wallet_send.py
+++ b/test/functional/wallet_send.py
@@ -31,10 +31,7 @@ class WalletSendTest(BitcoinTestFramework):
         # whitelist peers to speed up tx relay / mempool sync
         self.noban_tx_relay = True
         self.supports_cli = False
-        self.extra_args = [
-            ["-walletrbf=1", "-datacarriersize=16"],
-            ["-walletrbf=1", "-datacarriersize=16"]
-        ]
+        self.extra_args = [["-walletrbf=1", "-datacarriersize=16", "-deprecatedrpc=bip125"]] * self.num_nodes
         getcontext().prec = 8 # Satoshi precision for Decimal
 
     def skip_test_if_missing_module(self):