Hi!
Yesterday, my Signal app crashed on my Kompakt. (I had it installed via the .apk from Signal’s website.) I could not get the app working and had to reinstall it without any backup files, which resulted in losing all my data.
Today, I read a post on Signal’s Reddit about what this was all about. Allegedly, version 7.41.3 had a critical bug that caused it to crash, just like mine did. Signal has already pushed a newer .apk version on their website (7.41.4), which is not yet available on the Play Store/Aurora Store.
So, I just want to give a heads up to those using Signal about this update before your app crashes. Or, make sure to create a backup file. 
EDIT:
Make sure to use this command in the terminal:
adb install -r your_signal.apk
According to PerplexityAI the -r flag tells ADB to replace the existing app while preserving its data and settings. This is the safest and most common way to update an app outside of the Play Store without losing data.