This hasn't happened before the 12.3 update (was working great on 12.2) and it's nothing urgent like other stuff being posted here but here it is.

After the upgrade I logged to GNOME session, logged out, then logged to KDE to check something, logged out and when I got back to GNOME, Firefox (and other programs, such as Banshee) are using KDE libs. Again, it's not too bad but it can get annoying.
I installed KDE pattern while I was on 12.2 with GNOME base system (now I added E17 but that's another story)

example

How do I get it back to normal or will it be fixed via future update?

Thanks.