You will lose everything... Did you try uninstalling all of your apps, one by one and see if you find the culprit? Also, did you try going into safe mode and see if it keeps happening? Power menu - hold power off and it will pop up.
First of all, we apologize for any inconvenience you've experienced with the restarting issue.
Based on the error reports you've submitted, it seems that mail app has been triggering multiple network requests causing system reset even when the network is blocked.
You could try uninstalling app or changed the options below:
Background Data Usage: Settings > Apps > "Proton Mail" app > Mobile Data > Allow background data usage
Since some of your error reports that you've submitted were missing system log information (We're suspecting that because restart happened while you were sending the error report?), we may need more information from you by sending us the full log.
Factory Data Reset may be another possible alternative for your case; to find out which apps are causing this issue.
