I have completed the upgrade of my box from 13.1 to 13.2. However, I faced some minor issues and one of them is the title of my system in the grub menu, which is not openSUSE or 13.2 but 13.1!
The “Problem” is that sometime in the past I changed the grub menu and after that, all new installations/updates simply put an .rpmnew file.
So, the solution to the problem is to remove the _13.1 from the title:
cp /boot/grub2/grub.cfg ~/root # just a backup, you never know
sed -i 's/13.1/13.2/g' /etc/default/grub
grub2-mkconfig > /boot/grub2/grub.cfg
Note: Yes, the sed is not technically right, but it works.
It does not at all depend on the upgrade method, and the problem was already in 12.2 when grub2 was introduced (of course there was no upgrade yet back then, so the first time you saw it was when upgrading to 12.3).
@tsu2: a more general script has been suggested in bugzilla already (even twice I think), but this hasn’t been added to the package for whatever reasons.
13.2 sets “openSUSE” by default anyway, so that problem will not exist when you upgrade a fresh 13.2 installation to 13.3 or Tumbleweed.