For the Mastodon Android app, I also sometimes see crashes that make no sense. For example, how about native crashes, on a thread that is created and run by the system, that only contains system libraries in its stack trace, and that never ran any of my code because the app doesn't contain any native libraries to begin with?
Unfortunately I've never looked at crashes this way when I worked at VKontakte because there were just too many crashes overall. That app had tens of millions of users so it crashed a lot in absolute numbers no matter what I did.