[Wayland][multi-screen][NVIDIA] Black screen with 3 monitors on KWin 6.6.6; X11 works

[Méven]

Hi Mikael,

> Please let me know whether this should be filed as a new Bugzilla regression or attached to an existing report.

Please do that.
Try to find an existing one, and if you run out of patience create one.
You already found some possibly related bugs !

> , but I am reproducing the problem on KWin 6.6.6.

This version isn't supported by the KDE community anymore, but could
fall into the kubuntu LTS initiative scope, so worth reporting still.

> KWin detects the outputs, but the graphical session becomes black on all displays / applying the output configuration fails.

This sounds like a plasmashell crash.
I can recommend you to follow the steps for plasmashell in
https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports#Retrieving_a_backtrace_using_coredumpctl

Getting kwin logs would also be useful:
journalctl --user -u plasma-kwin_wayland.service

To add to your bug report.

Sincerely,

-- 
Méven