SUMMARY

Sometimes plasma gets into a state where when I click on something in the task manager to bring an already running application to the front, it will instead spawn a new instance of that application. This will happen for all running applications -- it becomes impossible to switch to an already running application (except via alt-tab).

Killing and re-starting Plasma fixes this. I've had this happen both immediately after login, and when the desktop geometry changes due to a screen being (un)plugged.

This only started happening when I switched to Wayland -- but that came with a big system update so it's not clear which of those changes started this.


STEPS TO REPRODUCE
1. With some applications (Firefox, Thunderbird, Konsole) running, click on one of their icons in the task manager


OBSERVED RESULT
A new instance of that application is being started.

EXPECTED RESULT
The existing window should be brought to the front.

SOFTWARE/OS VERSIONS
Operating System: Debian GNU/Linux 
KDE Plasma Version: 5.26.90
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8
Kernel Version: 6.1.0-2-amd64 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Xeon® CPU E3-1505M v5 @ 2.80GHz
Memory: 31,2 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics P530
Manufacturer: LENOVO
Product Name: 20ENCTO1WW
System Version: ThinkPad P50

ADDITIONAL INFORMATION