I found this other discussion here: Clear document history and reject old updates - #10 by ViktorQvarfordt and it sounds like Map is pretty expensive for random writes and it looks like YKeyValue would be more efficient, but also might be difficult for us to transition to.
I did end up doing a last write wins algo and not using YJS for this particular section of data and that’s working well. Otherwise, my doc was growing like 30MB per day (without even constant writing)