Bug report for existing functionality that does not work as intended. Signal was my default app, so to even receive an SMS I had to switch to Android Messages. I have been using the app for over half a decade and kept transferring messages from phone to phone. I fear it's because it's low on space (it has an SD card but afaik signal can't use that except for backups) and maybe something temporarily fills up the main storage and signal corrupts. I didn't get this in time. I checked and didn't have any signal updates or OS updates happen for at least a week, I don't think that was the issue.
The problem started one day with "... has joined Signal". (It is possible that the phone was low on storage on that day.) Subsequently I got this stack trace upon startup 4 out of 5 times, and 19 out of 20 times when trying to open any conversation: #10868 (comment) This instant crash made Signal unusable for the last few months. The backup procedure ran through within 1 second, and the created backup file is only 1 MB in size. Reinstalling Signal and trying to import that backup has no effect.