CPU is used 100% - Why?

Hello,

I have a VM and in this VM is only nextcloud 16.
This VM has 4 cores. Three cores are allways to 100%.
Why?

Thank you!
Michael

I have a similar problem:

NC is not reachable, but ssh is ok.
What to do, what can be the problem?

i would look into the nextcloud.log
and restart the php processes. maybe turn on maintenance mode before.