the command "bitcoin-cli getblockstats 0000000000000000000c61ff8f761ce509fc8901d3c22d61fec89637042ea2ba" does not work.

It displays "error: Error parsing JSON:0000000000000000000c61ff8f761ce509fc8901d3c22d61fec89637042ea2ba"

but it should display the block stats like the documentation says.

also bitcoin-cli getblockstats 0 does not work. block number must be at least 1 to work. But blocks start at 0.

tested with 0.20.1 on freebsd, another user on IRC acknowledged the problem.
{
    return RPCHelpMan{"getblockheader",
                "\nIf verbose is false, returns a string that is serialized, hex-encoded data for blockheader 'hash'.\n"
                "If verbose is true, returns an Object with information about blockheader <hash>.\n",
                {
                    {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
                    {"verbose", RPCArg::Type::BOOL, RPCArg::Default{true}, "true for a json object, false for the hex-encoded data"},
                },
                {
                    RPCResult{"for verbose = true",
                        RPCResult::Type::OBJ, "", "",
                        {
                            {RPCResult::Type::STR_HEX, "hash", "the block hash (same as provided)"},
                            {RPCResult::Type::NUM, "confirmations", "The number of confirmations, or -1 if the block is not on the main chain"},
                            {RPCResult::Type::NUM, "height", "The block height or index"},
                            {RPCResult::Type::NUM, "version", "The block version"},
                            {RPCResult::Type::STR_HEX, "versionHex", "The block version formatted in hexadecimal"},
                            {RPCResult::Type::STR_HEX, "merkleroot", "The merkle root"},
                            {RPCResult::Type::NUM_TIME, "time", "The block time expressed in " + UNIX_EPOCH_TIME},