SUMMARY
When using the "desktop zoom" effect and returning to the normal display (100%) after zooming in, sometimes the mouse pointer disappears. The mouse itself works normally, just the visible pointer either vanished or remains at the screen's center. And the pointer reappears in any zoom level > 100%.

STEPS TO REPRODUCE
1. Use a modern 4k display
2. Enable "Zoom" in systemsettings / desktop effects / accessibility.
3. Adjust settings to: 
     Zoom Factor: 1.10, Mouse Pointer: Keep, Mouse Tracking: Push
     Do not enable Focus Tracking nor Enable Text Cursor Tracking
4. Work normally with your desktop for about 1-2 hours, whilst regularly using the zoom function for a short time and returning to normal resolution after.

OBSERVED RESULT
Mouse pointer becomes invisible in normal resolution (or is displayed statically in the screen's center).
It even returns while changing to any zoom level > 100%, but only there.

EXPECTED RESULT
Mouse pointer stays visible and functional in all zoom levels as well as  in normal resolution.

SOFTWARE/OS VERSIONS
Linux Kernel:  5.6.0-1028-oem (64-bit)
KDE Plasma Version:  5.24.1
KDE Frameworks Version: 5.91.0
Qt Version: 5.15.3

ADDITIONAL INFORMATION
* Various commonly recommended methods to restore a lost pointer  (e.g. locking and unlocking the screen, switching to a TTY and back, unplugging and replugging the USB mouse) do NOT work. Only logging out and logging back in (i.e. restarting X11) brings the mouse pointer back in normal resolution.
*  As the pointer becomes visible again when zooming to > 100%, this indicates that actually only restoring the 100% cursor may fail.
* The effect occurred first at 2022-92-09. It could therefore have been 'rolled out' with the following packages (1-2 days before):
plasma-discover-common_5.24.0-0xneon+20.04+focal+release+build51_all.deb
plasma-discover-backend-snap_5.24.0-0xneon+20.04+focal+release+build51_amd64.deb
plasma-discover-backend-flatpak_5.24.0-0xneon+20.04+focal+release+build51_amd64.deb
plasma-discover_5.24.0-0xneon+20.04+focal+release+build51_amd64.deb
kde-config-updates_5.24.0-0xneon+20.04+focal+release+build51_amd64.deb
base-files_11ubuntu5.4+p20.04+trelease+git20220208.1239_amd64.deb
python-apt-common_2.0.0ubuntu0.20.04.7_all.deb

*  The following workaround exists: The "trackMouse" effect correctly circles the current position of the mouse cursor in normal resolution (and by the way, it is broken in any zoom level). Nevertheless, precise work is impossible this way.