diff --git a/doc/release-notes.md b/doc/release-notes.md
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -3,3 +3,11 @@
   <https://download.bitcoinabc.org/0.21.13/>
 
 This release includes the following features and fixes:
+
+Low-level changes
+=================
+
+Tests
+---
+
+- `-fallbackfee` was 0 (disabled) by default for the main chain, but 20000 by default for the test chains. Now it is 0 by default for all chains. Testnet and regtest users will have to add fallbackfee=20000 to their configuration if they weren't setting it and they want it to keep working like before. (#16524)
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -51,7 +51,8 @@
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-fallbackfee=<amt>",
                  strprintf("A fee rate (in %s/kB) that will be used when fee "
-                           "estimation has insufficient data (default: %s)",
+                           "estimation has insufficient data. 0 to entirely "
+                           "disable the fallbackfee feature. (default: %s)",
                            CURRENCY_UNIT, FormatMoney(DEFAULT_FALLBACK_FEE)),
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-keypool=<n>",
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -67,7 +67,7 @@
 //! -paytxfee default
 constexpr Amount DEFAULT_PAY_TX_FEE = Amount::zero();
 //! -fallbackfee default
-static const Amount DEFAULT_FALLBACK_FEE(20000 * SATOSHI);
+static const Amount DEFAULT_FALLBACK_FEE = Amount::zero();
 //! -mintxfee default
 static const Amount DEFAULT_TRANSACTION_MINFEE_PER_KB = 1000 * SATOSHI;
 //! minimum recommended increment for BIP 125 replacement txs
@@ -1373,7 +1373,7 @@
 
     CFeeRate m_pay_tx_fee{DEFAULT_PAY_TX_FEE};
     bool m_spend_zero_conf_change{DEFAULT_SPEND_ZEROCONF_CHANGE};
-    //! will be defined via chainparams
+    //! will be false if -fallbackfee=0
     bool m_allow_fallback_fee{true};
     // Override with -mintxfee
     CFeeRate m_min_fee{DEFAULT_TRANSACTION_MINFEE_PER_KB};
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -4909,7 +4909,6 @@
         walletInstance->m_min_fee = CFeeRate(n);
     }
 
-    walletInstance->m_allow_fallback_fee = Params().IsTestChain();
     if (gArgs.IsArgSet("-fallbackfee")) {
         Amount nFeePerK = Amount::zero();
         if (!ParseMoney(gArgs.GetArg("-fallbackfee", ""), nFeePerK)) {
@@ -4926,10 +4925,11 @@
                     .translated);
         }
         walletInstance->m_fallback_fee = CFeeRate(nFeePerK);
-        // disable fallback fee in case value was set to 0, enable if non-null
-        // value
-        walletInstance->m_allow_fallback_fee = (nFeePerK != Amount::zero());
     }
+    // Disable fallback fee in case value was set to 0, enable if non-null value
+    walletInstance->m_allow_fallback_fee =
+        walletInstance->m_fallback_fee.GetFeePerK() != Amount::zero();
+
     if (gArgs.IsArgSet("-paytxfee")) {
         Amount nFeePerK = Amount::zero();
         if (!ParseMoney(gArgs.GetArg("-paytxfee", ""), nFeePerK)) {
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -359,6 +359,7 @@
         f.write("[{}]\n".format(chain_name_conf_section))
         f.write("port=" + str(p2p_port(n)) + "\n")
         f.write("rpcport=" + str(rpc_port(n)) + "\n")
+        f.write("fallbackfee=0.0002\n")
         f.write("server=1\n")
         f.write("keypool=1\n")
         f.write("discover=0\n")