SUMMARY
I have laptop + external display setup. X11 session.
After updating to Plasma 6, I cannot longer quickly manage my screens through "shortcuts" - either Meta+P or "Display Configuration" option in system tray. Selecting "Switch to external screen", "Switch to laptop screen", "Extend to left" or "Extend to right" does nothing.
In order to configure my displays the way I want, now I have to right click on desktop > select "Configure Display Settings" and explicitly check and apply what is primary display or what display I want to disable.

STEPS TO REPRODUCE
1. Hit Meta + P or under system tray click "Display Configuration"
2. Select any option, like "Switch to external screen"

OBSERVED RESULT
Nothing happens

EXPECTED RESULT
Selecting appropriate option should work - i.e. disable external/built-in screen, extend screen to left/right

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 6.0.2
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2

ADDITIONAL INFORMATION
This functionality worked perfectly under Plasma 5