Created attachment 132263 [details]
Screen recording showcasing the glitch

SUMMARY
Application Launcher entries become invisible if you switch back and forth quickly between menus and their sub-menus, before the switching animation completes. (see attached video)

STEPS TO REPRODUCE
1. Open "Application Launcher".
2. Go to "Applications".
3. Enter into a sub-menu. (eg. "Games")
4. Immediately go back using the arrow keys. (before the switching animation finishes)

OBSERVED RESULT
All entries in the "Applications" menu become more and more transparent, until they become very difficult to see.

EXPECTED RESULT
All entries in the "Applications" menu remain visible.

SOFTWARE/OS VERSIONS 
Linux: 5.8.5-arch1-1 
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.73.0
Qt Version: 5.15.0

ADDITIONAL INFORMATION
Issue persists with compositor turned off. (the switching animation is still displayed, even with the compositor turned off)
Issue persists on a new user with default config.
A plasmashell restart is required to revert back to normal.
The "Application Launcher" is still functional.
First came across this glitch in Plasma version 5.19.3?