Created attachment 159177 [details]
screencast of the bug

SUMMARY
I set the panel auto-hide. When I press hotkey to pop up the Kickoff, both the panel's and the widget's popup animation play at the same time, but the widget's animation begins at the final position of the panel, so during the animation, there's a gap between the two.


STEPS TO REPRODUCE
1. Set the bottom panel to auto-hide.
2. Press Kickoff's hotkey.

OBSERVED RESULT
During the animation, there's a gap between the panel and Kickoff.

EXPECTED RESULT
No gap. Kickoff popup should always touch the panel during the animation.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.106.0
Qt Version: 5.15.9