For some reason, after this update and a few extra steps, KDE / SDDM and the console didn’t allow me to sign in anymore.
It seems like the /etc/shadow file was changed, and my password hash was replaced with something like “username:pend[…some other characters]” (can’t tell exactly anymore).
I don’t know exactly how this happened, but I can tell that before I rebooted after the upgrade, I tried to add my user to another group.
I logged out and in again, but I couldn’t see myself in the new group when I executed groups.
So I tried it again, and this time my sudo password wasn’t accepted anymore.
So I tried changing my password using the KDE settings which wasn’t working as well and the dialog told me that I have to wait for 10 minutes, before I can try again.
In the end, this comment helped me to fix the situation: Locked out of account - please help! - #6 by linux-aarhus
The passwd file wasn’t changed, but the shadow file was and I was able to restore my hash (?) using the /etc/shadow- backup
I didn’t use any tool to merge pacnew files, nor did I manually edit passwd/ shadow file before.