Thanks for the hints, i checked last 10 boots.yes - exactly! - this is why it's really odd that the service vanished - I'd suggest to check your journal (a few boots before the 6.8 kernel) - to see if the service used to exist - and maybe also check /var/log/apt/term.log if there's any indication that the service got removed during upgrade (it should not)
but glad your system is running fine!
The zfs-import@HDD-SATA service was missing already in all 10 last boots, so it was never there actually.
So i would say that i something weird happened or i deleted that pool and recreated it, but even then the service wont get deleted normally on zpool destroy.
Doesn't matter, the service is my fault.
But what i don't get is, the pool was definitively imported still automatically somehow, because i would have seen it instantly, if not. The question is then, why it wasn't get imported anymore then after the update.
However, it doesn't matter anyway, because its definitively something weird i did, so i have to find out myself.
Thanks for the hints @Stoiko Ivanov
Cheers