Suzune

It can run for days and puts additional strain on the hardware.

Check the physical attachment and obvious hardware failures first.

In case the hardware seems fine, try to zfs send the most important data to a safe place.

Yes, I referred to the Debian part only.

I’ve seen that the patches are only available in the debian-security repository. It’s important to review your repo list in /etc/apt/sources.list.d.