I am relaying a privacy issue for Bitcoin Core that was [reported on r/Bitcoin](https://reddit.com/r/Bitcoin/comments/klk2wh) (Reddit).

The [message](https://pastebin.com/raw/ptFQityt) was:

- _Using coin control_
- _Custom change address_

_When one clicks the increase transaction fee button, it adds another input rather than increasing the fee by reducing the change output. Major privacy leak since you have no control of the input used._

From that it sounds like the observed behavior is that the replacement transaction includes an additional UTXO that was not chosen by the user, even though the transaction was composed as a Coin Control transaction.

So I'm assuming the expected behavior would be for Bitcoin Core to remember that this OUTPUT was actually a Custom Change Address and to then lower the amount of that OUTPUT by the amount needed for the fee bump.

And, now that I am thinking of this, isn't there the expectation that if my initial transaction was done using Coin Control, and then if my fee bump (RBF) needs another UTXO input to cover the increase in fee, that Coin Selection for that will occur (regardless of whether or not the change address was a Custom Change Address)?  
RPCArgOptions{.oneline_description="options"}},
        },
        RPCResult{
            RPCResult::Type::OBJ, "", "",
                {
                    {RPCResult::Type::BOOL, "complete", "If the transaction has a complete set of signatures"},
                    {RPCResult::Type::STR_HEX, "txid", true, "The transaction id for the send. Only 1 transaction is created regardless of the number of addresses."},
                    {RPCResult::Type::STR_HEX, "hex", true, "If add_to_wallet is false, the hex-encoded raw transaction with signature(s)"},
                    {RPCResult::Type::STR, "psbt", true, "If more signatures are needed, or if add_to_wallet is false, the base64-encoded (partially) signed transaction"}
                }
        },
        RPCExamples{""
        "\nSend 0.1 BTC with a confirmation target of 6 blocks in economical fee estimate mode\n"
        + HelpExampleCli("send", "'{\"" + EXAMPLE_ADDRESS[0] + "\": 0.1}' 6 economical\n") +
        "Send 0.2 BTC with a fee rate of 1.1 " + CURRENCY_ATOM + "/vB using positional arguments\n"
        + HelpExampleCli("send", "'{\"" + EXAMPLE_ADDRESS[0] + "\": 0.2}' null \"unset\" 1.1\n") +
        "Send 0.2 BTC with a fee rate of 1 " + CURRENCY_ATOM + "/vB using the options argument\n"
        + HelpExampleCli("send", "'{\"" + EXAMPLE_ADDRESS[0] + "\": 0.2}' null \"unset\" null '{\"fee_rate\": 1}'\n") +
        "Send 0.3 BTC with a fee rate of 25 " + CURRENCY_ATOM + "/vB using named arguments\n"
        + HelpExampleCli("-named send", "outputs='{\"" + EXAMPLE_ADDRESS[0] + "\": 0.3}' fee_rate=25\n") +
        "Create a transaction that should confirm the next block, with a specific input, and return result without adding to wallet or broadcasting to the network\n"
        + HelpExampleCli("send", "'{\"" + EXAMPLE_ADDRESS[0] + "\": 0.1}' 1 economical '{\"add_to_wallet\": false, \"inputs\": [{\"txid\":\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\", \"vout\":1}]}'")
        },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
        {
            std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
            if (!pwallet) return UniValue::VNULL;
            UniValue options{request.params[4].isNull() ? UniValue::VOBJ : request.params[4]};
            InterpretFeeEstimationInstructions(request.params[1], request.params[2], request.params[3], options);
            PreventOutdatedOptions(options);