Created attachment 127191 [details]
screenshot

SUMMARY
This issue affects both Arch Linux (Plasma 5.18.4) and Neon unstable edition,
but I can't reproduce consistently. If you fail to reproduce, repeat the steps below trying to assign a different shortcut that also includes Meta key.

STEPS TO REPRODUCE
1. open the settings window of an applet in systray (sound, for example)
2. in "keyboard shortcuts" section, try to assign any shortcut including Meta
key and that is not in use yet: as we can see in the attached screenshot, button to assign the shortcut shows the pressed shortcut twice.
3. click on "Cancel" button of "<applet> settings" window
4. try to assign the same shortcut to the same applet again: now the button to assign the shortcut shows the pressed shortcut once as expected

SOFTWARE/OS VERSIONS
Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.18.80
KDE Frameworks Version: 5.69.0
Qt Version: 5.14.1


ADDITIONAL INFORMATION
Despite the pressed shortcut is duplicated after the step 2, it works as expected if confirmed with click on "Ok" button of "<applet> settings" window.