Created attachment 165521 [details]
'task bar' leaves ghost as evident by the ability to 'right-click' desktop and get application menu

SUMMARY
plasma 5 desktop (leap 15.5 dup from 15.4) 'task manager' panel set to 'auto hide' leaves an exact 'ghost' of itself on desktop when it 'hides'.
toggling compositor or scrolling (switching) desktops is the Only way to 'repaint' the affected area (get rid of it). this is beyond annoying, but not critical, yet.


STEPS TO REPRODUCE
1. set 'task manager' main panel to 'auto hide'
2. activate panel with mouse 
3. leave panel area, click somewhere else

OBSERVED RESULT
a 'ghost' of the main panel (task manager) remains on screen
it is Not being repainted or erased.
you can see in attached image that i am able to right-click desktop where it appears 'task bar is' and get my application menu, the same as i'm clicking on desktop.
the Only way to make it 'go away' is to toggle compositor or scroll to different desktop, then back.
- very annoying, but not critical as it does not seem to affect anything else.

EXPECTED RESULT
it would hide and not be seen again until activated

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSuSE 15.5
(available in About System)
KDE Plasma Version: 5.27.9
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8

ADDITIONAL INFORMATION
kernel vers: 5.14.21-150500.55.44-default (64-bit)
Processor: 8 × Intel® Core™ i7-8565U CPU @ 1.80GHz
Graphics Driver: Mesa (i believe, as that's all that's offered)
Graphics Platform: X11