Feairphone 5 stuck in soft restart loop

After the last OS update my FP5 got very unstable. E.g. it would soft restart (show the murena boot animation) when a notification by the Signal app was going to be displayed. I had to disable notifications in Signal.
Now I tried to setup an alarm and the phone is constantly soft rebooting and even completely crashing and full rebooting. Is there a way to get out of this?