ID.unique() returns "Document with the requested ID already exists. Try again with a different ID"

So out of nowhere ID.unique() doesn't work now, I haven't changed any code in my cloud functions for couple of weeks, but now createDocument with ID.unique() would gives me error "Document with the requested ID already exists. Try again with a different ID". Tried to upgrade node sdk from 12.0.0 to 14.0.0, and from 14.0.0 back to 12.0.0, tried to upgrade appwrite from 1.5.10 to 1.6.0. Neither works, what I did notice is that docker logs didn't generate appwrite-specific errors, except bunch of redis errors. I am not sure if the redis is the problem since idk how to flush cache. Does anyone has encountered this weird behaviors before and know a solution? Help appreciated, thanks! Working with Node SDKs and Cloud Functions.