When doing the same as āDecaTecā has done, i recognize some php8.0 installations. Iām feared now. I remember having seen similar on my nextcloud predecessor instance when doing some regular updates and the the server became unusable. I donāt know if it does not boot at all but in any case i canāt ssh anymore as well as connect NC-Instance. It was Raspberry Pi 3B with 32bit OS, NC20. Recent instance (new from scratch) is NC21 on RPI 4B 64bit OS.
Iām feared to reboot now 
Does your server behave as expected?
Suggestions welcome, thx