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.
{
    if (options.exists("input_weights")) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Input weights should be specified in inputs rather than in options.");
    }
    if (inputs.size() == 0) {
        return;
    }
    UniValue weights(UniValue::VARR);
    for (const UniValue& input : inputs.getValues()) {
        if (input.exists("weight")) {
            weights.push_back(input);
        }
    }
    options.pushKV("input_weights", weights);
}
RPCHelpMan fundrawtransaction()