Hi WR, love your work lately.
The current consensus limit is 223 bytes in an OP_RETURN script, but this includes the OP_RETURN opcode, and the push instruction which is 1 byte for less than 73 bytes and 2 bytes (OP_PUSHDATA <datalength>) for anything more, so is fundamentally limited to 220B of actual data. That limit also includes any push instructions that you might include to help explorers parse your data. This was a limitation we hit a lot at Tokenized.
Ping me if you want more info. I can show you how we use the data carrier in our protocol.
