Created attachment 172163 [details]
The Plasma shell backtrace

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***

SUMMARY
I have a laptop and an external monitor connected via HDMI cable. Both have 1920x1080 resolution, the laptop's screen has 125% scaling, when the external one has 100%. The thing is everytime when I unplug the HDMI, the shell switches successfully all apps to the main screen of the laptop, but after 3ish seconds it crashes (the task bar disappears), then restores and everything is alright on one screen. After the connection of the cable, no crashes occurs: two screens works normally.

STEPS TO REPRODUCE
1. Connect the second monitor via HDMI.
2. Unplug it.
3. The Plasma shell crashes.

OBSERVED RESULT
After the moving all windows to the main screen around 3 seconds leave, and the Plasma shell crashes, then restores itself.

EXPECTED RESULT
No crashes while unplugging an external monitor.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Linux 40
KDE Plasma Version: 6.1.3
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.2

ADDITIONAL INFORMATION
Kernel Version: 6.9.11-200.fc40.x86_64 (64-bit)
Graphics Platform: Wayland