SUMMARY I have noticed that on latest KDE Neon Testing, the lower half of the gray background of the Plasm applets' headers are displayed with a second delay. SOFTWARE/OS VERSIONS Linux/KDE Plasma: KDE Neon Testing KDE Plasma Version: 5.23.90 KDE Frameworks Version: 5.91.0 Qt Version: 5.15.3 Wayland ADDITIONAL INFORMATION
Created attachment 145773 [details] Screenshot: The gray area is not there yet...
Can confirm. This animation is intentional when switching between applets in the system tray. However it's not necessary to run for the first applet shown.
This has been fixed as to be almost un-noticeable anymore, even with an extremely slow animation speed.