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.
{
    RPCHelpMan{
                "getrawtransaction",
                "\nReturn the raw transaction data.\n"
                "\nBy default this function only works for mempool transactions. When called with a blockhash\n"
                "argument, getrawtransaction will return the transaction if the specified block is available and\n"
                "the transaction is found in that block. When called without a blockhash argument, getrawtransaction\n"
                "will return the transaction if it is in the mempool, or if -txindex is enabled and the transaction\n"
                "is in a block in the blockchain.\n"