Hello,
Re:
Operating System: Debian GNU/Linux 11 (Q4OS)
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.2
Kernel Version: 5.10.0-10-amd64
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-4460 CPU @ 3.20GHz
Memory: 7.7 GiB of RAM
Graphics Processor: GeForce GT 710/PCIe/SSE2

After a fresh installation of the Q4OS 4.7 Gemini stable, I am experiencing frequent 'crashes' due to a Segmentation fault.

Details:
Executable: kwin_x11 PID: 2412 Signal: Segmentation fault (11).
(Unfortunately, "The crash information could not be generated".)

The following applications are usually used during the crash: Firefox, Thundebird, KWrite, LibreOffice calc and VLC.

Switching from OpenGL 2.0 to Xrender or OpenGL 3.1 does not make any difference and "Scale method "Accurate" is not supported by all hardware and can cause performance regressions and rendering artifacts." Also, the Desk Cube Animation does not work anymore.

I logged out of the Plasma session Ctrl-Alt-F2 and performed:
sudo apt-get update && sudo apt-get dist-upgrade
sudo apt-get clean && sudo apt-get autoclean && sudo apt-get update && sudo apt-get upgrade but this didn't make any difference either.

I ran [root@desktop:~# sudo memtester 1024 5] which did not produce any issues.

The KSystemLog produced the following information:
System Log
5/1/22 12:17 PM jomtien CRON[12759] (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
5/1/22 12:18 PM jomtien dbus-daemon[2315] [session uid=1000 pid=2315] Activating service name='org.kde.KSplash' requested by ':1.103' (uid=1000 pid=12770 comm="/usr/bin/kwin_x11 --crashes 1 ")
5/1/22 12:19 PM jomtien org.kde.KSplash[12784] org.kde.knotifications: WaitForName: Service was not registered within timeout
5/1/22 12:19 PM jomtien dbus-daemon[2315] [session uid=1000 pid=2315] Activated service 'org.kde.KSplash' failed: Process org.kde.KSplash exited with status 1
===
Daemons' Logs
5/1/22 12:18 PM jomtien dbus-daemon[2315] [session uid=1000 pid=2315] Activating service name='org.kde.KSplash' requested by ':1.103' (uid=1000 pid=12770 comm="/usr/bin/kwin_x11 --crashes 1 ")
5/1/22 12:19 PM jomtien dbus-daemon[2315] [session uid=1000 pid=2315] Activated service 'org.kde.KSplash' failed: Process org.kde.KSplash exited with status 1
===
Journald Log
5/1/22 12:18 PM dbus-daemon [session uid=1000 pid=2315] Activating service name='org.kde.KSplash' requested by ':1.103' (uid=1000 pid=12770 comm="/usr/bin/kwin_x11 --crashes 1 ")
5/1/22 12:19 PM org.kde.KSplash org.kde.knotifications: WaitForName: Service was not registered within timeout
5/1/22 12:19 PM dbus-daemon [session uid=1000 pid=2315] Activated service 'org.kde.KSplash' failed: Process org.kde.KSplash exited with status 1
===end===

Please note that this Segmentation fault is happening to 2 desktop and 1 laptop computer(s). I re-installed Q4OS thrice using a USB stick formatted with Gparted to fat32 to which the newly downloaded q4os-4.7-x64.r1.iso image was written with the (mint-stick) USB Writer.

I feel out of my depth dealing with this situation and request assistance for a suitable fix.

You can find more information on how to debug KWin here: https://community.kde.org/KWin/Debugging

FWIW: this should be reported to the bug tracker at https://bugs.kde.org for the product KWin, the forum is the wrong place for it.

Moving this to the KWin subforum.

Thanks for moving my post to the pertinent subforum.

I did not think debugging was required as the crash information could not be generated.

Anyway, at long last, I might have solved this nagging issue. After resetting the Splash Screen to default and removing the splash screen downloadable in System Settings the crashing of KWin ceased or at least I hope so.