Created attachment 873946 [details]
History of sudo zypper -v dup --allow-vendor-change

Hello, 

After unsuccessful attempts to upgrade to Plasma 6 (see bug 1221515), I've
finally been able to give it a go.

The upgrade went well until the reboot.

First of all, SDDM didn't display the theme and an error message in red
indicating that it couldn't find a file.

I logged into TTY and searched for and installed the missing RPMs, which are
not installed by default:
- libQt6QuickLayouts6
- libQt6Xml6
- libQt6Svg6

From there SDDM displays the theme. By entering login + password, there is a
connection attempt then back to Greeter with Wayland as X11.

In TTY , I found that libQt6Core5Compat6 was missing for wayland. 

I was able to launch a plasma 6 session under wayland with an ugly display that
didn't respect the theme colours, among other oddities.

However, with X11 I get a black screen for SDDM. So I can't connect.

So reboot + snapper rollback to plasma 5 for now.

I attach the upgrade history for information.