If I create an RBF transaction using the Qt GUI but specify my own custom change address, bumpfee doesn't work because it claims it can't find the change address:

    "Transaction does not have a change output"

This is because none of the outputs satisfy

    pWallet->IsChange(...)

I see there's a "TODO" commented in `CWallet::IsChange()` in `src/wallet/wallet.cpp`:

    // TODO: fix handling of 'change' outputs. The assumption is that any
    // payment to a script that is ours, but is not in the address book
    // is change.

I tend to put all my addresses in the address book whether I'm going to use them as change or not. I guess if the wallet was capable of creating its own SegWit change addresses I'd stop using custom change addresses, but currently it always seems to send change to a legacy address if I don't manually specify a change address.
{
    return RPCHelpMan{"fundrawtransaction",
                "\nIf the transaction has no inputs, they will be automatically selected to meet its out value.\n"
                "It will add at most one change output to the outputs.\n"
                "No existing outputs will be modified unless \"subtractFeeFromOutputs\" is specified.\n"
                "Note that inputs which were signed may need to be resigned after completion since in/outputs have been added.\n"
                "The inputs added will not be signed, use signrawtransactionwithkey\n"
                "or signrawtransactionwithwallet for that.\n"
                "All existing inputs must either have their previous output transaction be in the wallet\n"
                "or be in the UTXO set. Solving data must be provided for non-wallet inputs.\n"
                "Note that all inputs selected must be of standard form and P2SH scripts must be\n"
                "in the wallet using importaddress or addmultisigaddress (to calculate fees).\n"
                "You can see whether this is the case by checking the \"solvable\" field in the listunspent output.\n"
                "Only pay-to-pubkey, multisig, and P2SH versions thereof are currently supported for watch-only\n",
                {
                    {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex string of the raw transaction"},
                    {"options", RPCArg::Type::OBJ_NAMED_PARAMS, RPCArg::Optional::OMITTED, "For backward compatibility: passing in a true instead of an object will result in {\"includeWatching\":true}",
                        Cat<std::vector<RPCArg>>(
                        {
                            {"add_inputs", RPCArg::Type::BOOL, RPCArg::Default{true}, "For a transaction with existing inputs, automatically include more if they are not enough."},
                            {"include_unsafe", RPCArg::Type::BOOL, RPCArg::Default{false}, "Include inputs that are not safe to spend (unconfirmed transactions from outside keys and unconfirmed replacement transactions).\n"
                                                          "Warning: the resulting transaction may become invalid if one of the unsafe inputs disappears.\n"
                                                          "If that happens, you will need to fund the transaction with different inputs and republish it."},
                            {"minconf", RPCArg::Type::NUM, RPCArg::Default{0}, "If add_inputs is specified, require inputs with at least this many confirmations."},
                            {"maxconf", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "If add_inputs is specified, require inputs with at most this many confirmations."},