File system check -> WTF?

Background: i’ve got Hassos running on proxmox backed by ZFS storage.
I don’t know how or why, but a while ago i started cleaning up some old ZFS snapshots and something went wrong. Some of my VMs got some data corruption, even though ZFS doesn’t indicate any checksum- or other errors.

Anyway, ever since Homeassistant has been having some instability issues, and upon checking the logs, i found out that there were some file system errors logged on boot for the sda8 partition.

Now something weird is going on with that partition, I’ve been managing linux servers for over 20 years now, but never seen this:

mount | grep sda8
/dev/sda8 on /mnt/data type ext4 (rw,relatime,commit=30)
/dev/sda8 on /var/lib/docker type ext4 (rw,relatime,commit=30)
/dev/sda8 on /var/log/journal type ext4 (rw,relatime,commit=30)
ls /mnt/data
docker forcefsck logs lost+found raunc.db supervisor swapfile
ls /var/lib/docker
buildkit containers forcefsck network plugins swarm trust
containerd engine-id image overlay2 runtimes tmp volumes
ls /var/log/journal
ba5f39838bc74fe19f860fad4b13ce68 forcefsck

So different contents on three mountpoints even though they point to the same filesystem?

Anyway, i’ve placed forcefsck files in all three of these, but no filesystem check gets run on reboot, still leaving me with a corrupted filesystemd.

So my questions:

  1. What’s up with different contents per mountpoint?
  2. How to run a filesystem check on sda8?