I am left without network device after rollback about snapper-rollback HOT 1 CLOSED

Is this normal

Clearly not.

or am I doing something wrong?

Not necessarily either.

I'm not sure why your network interfaces broke, then again that's very much out of scope of what this script does. The wiki recommends reading the announcements mailing list before upgrading, I'm not sure if that could help you narrow down what the issue is here.

Another avenue you might want to explore is getting an actual repro case. Anyone else running pacman -Syu followed by a rollback is unlikely to have the same problem. Having an answer to "If you needed to repro this on a different machine, how would you do so?" would help you identify the root cause.
That being said, there's probably more straightforward ways to go about things 1 2

Good luck!

from snapper-rollback.