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.
"       },\n"
            "       \"sequence\": n      (numeric) The script sequence number\n"
            "       \"txinwitness\": [\"hex\", ...] (array of string) hex-encoded witness data (if any)\n"
            "     }\n"
            "     ,...\n"
            "  ],\n"
            "  \"vout\" : [              (array of json objects)\n"
            "     {\n"
            "       \"value\" : x.xxx,            (numeric) The value in " + CURRENCY_UNIT + "\n"
            "       \"n\" : n,                    (numeric) index\n"
            "       \"scriptPubKey\" : {          (json object)\n"
            "         \"asm\" : \"asm\",          (string) the asm\n"
            "         \"hex\" : \"hex\",          (string) the hex\n"
            "         \"reqSigs\" : n,            (numeric) The required sigs\n"
            "         \"type\" : \"pubkeyhash\",  (string) The type, eg 'pubkeyhash'\n"
            "         \"addresses\" : [           (json array of string)\n"
            "           \"address\"        (string) bitcoin address\n"
            "           ,...\n"
            "         ]\n"
            "       }\n"
            "     }\n"
            "     ,...\n"
            "  ],\n"
            "  \"blockhash\" : \"hash\",   (string) the block hash\n"
            "  \"confirmations\" : n,      (numeric) The confirmations\n"
            "  \"blocktime\" : ttt         (numeric) The block time in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"time\" : ttt,             (numeric) Same as \"blocktime\"\n"
            "}\n"
                    },
                },