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.
{
                                    {"address", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "A key-value pair. The key (string) is the bitcoin address, the value (float or string) is the amount in " + CURRENCY_UNIT},
                                },
                                },
                            {"", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED, "",
                                {
                                    {"data", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "A key-value pair. The key must be \"data\", the value is hex-encoded data"},
                                },
                                },
                        },
                        },
                    {"locktime", RPCArg::Type::NUM,  "0", "Raw locktime. Non-0 value also locktime-activates inputs"},
                    {"replaceable", RPCArg::Type::BOOL,  "false", "Marks this transaction as BIP125-replaceable.\n"
            "                             Allows this transaction to be replaced by a transaction with higher fees. If provided, it is an error if explicit sequence numbers are incompatible."},
                },
                RPCResult{
            "\"transaction\"              (string) hex string of the transaction\n"
                },
                RPCExamples{
                    HelpExampleCli("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\" \"[{\\\"address\\\":0.01}]\"")
            + HelpExampleCli("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\" \"[{\\\"data\\\":\\\"00010203\\\"}]\"")
            + HelpExampleRpc("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\", \"[{\\\"address\\\":0.01}]\"")
            + HelpExampleRpc("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\", \"[{\\\"data\\\":\\\"00010203\\\"}]\"")
                },
            }.Check(request);
    RPCTypeCheck(request.params, {
        UniValue::VARR,
        UniValueType(), 
        UniValue::VNUM,
        UniValue::VBOOL