I’ve upgraded a bunch of different boxes having an assorted hardware in them and I’ve had several failures - most of the boxes in question have been 12.1 or 12.2 ones, removed repos, cleaned, zypper dup’d (twice) to make sure everything went alright and ALL the failed ones have had the same issue, initrd build has failed to contain the proper drivers for the hardware.
For some reason the rebuilding has “forgotten” some chipset drivers although the previous ones have had no issues. It’s a really nasty problem and one that’s taken some manual fixing 
Also Grub2 seems to have some issues, it doesn’t cleanly migrate all the old information but retains several kernel lines that no longer exist - and has them as default. Not a big one that but if you remotely upgrade the server, you’ll end up with a non-booting system, which is bad.