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{"verifytxoutproof",
                "\nVerifies that a proof points to a transaction in a block, returning the transaction it commits to\n"
                "and throwing an RPC error if the block is not in our best chain\n",
                {
                    {"proof", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex-encoded proof generated by gettxoutproof"},
                },
                RPCResult{
            "[\"txid\"]      (array, strings) The txid(s) which the proof commits to, or empty array if the proof can not be validated.\n"
                },
                RPCExamples{""},
            }.Check(request);
    CDataStream ssMB(ParseHexV(request.params[0], "proof"), SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS);
    CMerkleBlock merkleBlock;
    ssMB >> merkleBlock;
    UniValue res(UniValue::VARR);
    std::vector<uint256> vMatch;
    std::vector<unsigned int> vIndex;
    if (merkleBlock.txn.ExtractMatches(vMatch, vIndex) != merkleBlock.header.hashMerkleRoot)
        return res;
    LOCK(cs_main);
    const CBlockIndex* pindex = LookupBlockIndex(merkleBlock.header.GetHash());
    if (!pindex || !::ChainActive().Contains(pindex) || pindex->nTx == 0) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found in chain");
    }
    
    if (pindex->nTx == merkleBlock.txn.GetNumTransactions()) {
        for (const uint256& hash : vMatch) {
            res.push_back(hash.GetHex());