Created attachment 138700 [details]
Screenshot showing the issue

SUMMARY
Using Display scaling in the Wayland session also changes the physical resolution of the screen that is reported in the area that shows the relative positions of monitors (see attached screenshot). This behaviour is different from that in the X11 session.

STEPS TO REPRODUCE
1. Login to a Wayland session
2. Go to System Settings > display and monitor > display configuration
3. Move the display scaling slider

OBSERVED RESULTS
The screen resolution displayed in the top view (that shows the relative positions of displays) changes (see attached screenshot).

EXPECTED RESULTS
Behaviour should be similar to X11, where the actual physical resolution is displayed in the aforementioned area even while using display scaling.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.21.90
KDE Frameworks Version: 5.82.0
Qt Version: 5.15.2
Kernel Version: 5.10.38-1-lts (64-bit)
Graphics Platform: X11
Processors: 8 × AMD Ryzen 5 3500U with Radeon Vega Mobile Gfx
Memory: 21.5 GiB of RAM
Graphics Processor: AMD Radeon™ Vega 8 Graphics

ADDITIONAL INFORMATION
Also reproducible in KDE Neon.