SUMMARY
After update 5.22.5, the Application Launcher/Application Menu cannot be opened by pressing the Meta key anymore

STEPS TO REPRODUCE
1. Update to Plasma version 5.22.5
2. Have a button for the application launcher (Kickoff) or application menu (kicker) on your taskbar
3. Hit the Meta key (aka Windows key, the one between Ctrl and Alt on most keyboards). 

OBSERVED RESULT
Nothing happens. 

EXPECTED RESULT
The application menu or launcher should open upon pressing the Meta key. 

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: 
(available in About System)
Operating System: Arch Linux
KDE Plasma Version: 5.22.5
KDE Frameworks Version: 5.86.0
Qt Version: 5.15.2
Kernel Version: 5.14.5-arch1-1 (64-bit)
Graphics Platform: X11

ADDITIONAL INFORMATION
No changes have been made to the default key mapping. Reverting key mapping to defaults did not solve the problem. 
I also tried right-clicking the launcher/menu shortcut and opening its settings to manually change the keyboard shortcut. However, the dialog refuses to accept plain Meta as a keyboard shortcut. It expects a combination of two or more keys. 

(Sorry for opening this issue for version 5.22.4 instead of 5.22.5; that option is not available in the dialog)