When the newly introduced `"maxfeerate"` option is not passed, the default fee rate is interpreted as an absolute amount. However, when it is passed, it is interpreted as a fee rate. Thus, the rpc will return different results when the value is explicitly set to the default.

See

https://github.com/bitcoin/bitcoin/blob/536590f358dc3d3e5821eba7f1009452ea93b205/src/rpc/rawtransaction.cpp#L797-L807

I think we should change it back to an absolute value in BTC (not a feerate)

This was changed to a feerate by @kallewoof, so ping him to see if there was a specific reason to switch.
std::vector<std::vector<unsigned char>> solutions_data;
            txnouttype which_type = Solver(script, solutions_data);
            
            
            if ((which_type == TX_PUBKEY) || (which_type == TX_MULTISIG)) {
                for (const auto& solution : solutions_data) {
                    if ((solution.size() != 1) && !CPubKey(solution).IsCompressed()) {
                        return r;
                    }
                }
            }
            UniValue sr(UniValue::VOBJ);
            CScript segwitScr;
            if (which_type == TX_PUBKEY) {
                segwitScr = GetScriptForDestination(WitnessV0KeyHash(Hash160(solutions_data[0].begin(), solutions_data[0].end())));
            } else if (which_type == TX_PUBKEYHASH) {
                segwitScr = GetScriptForDestination(WitnessV0KeyHash(solutions_data[0]));
            } else {
                
                
                segwitScr = GetScriptForDestination(WitnessV0ScriptHash(script));
            }
            ScriptPubKeyToUniv(segwitScr, sr,  true);
            sr.pushKV("p2sh-segwit", EncodeDestination(ScriptHash(segwitScr)));
            r.pushKV("segwit", sr);
        }
    }
    return r;
}
static UniValue combinerawtransaction(const JSONRPCRequest& request)