Well I can't for sure prove it's indeed DB corruption, but I don't have many other theories.

It's unlikely to be a "static" bug affecting everyone because it would've been caught in QA and/or user reports and fixed already (this is not a new issue, been happening for a year at least).

Therefore my hypothesis is that it's dependent on corrupt persistent data that a relative minority of users have which is not easy for Apple to detect/replicate.