SUMMARY
It's hard to describe, but in KDE plasma 5.21, dragging a window with wobbly windows effect turned out and zoomed-in breeze window decorations does not look smooth around the window buttons.

STEPS TO REPRODUCE
1. Configure KDE to use breeze window icons with bigger size than normal, and to have the wobbly window effect when dragging windows.
2. Pick some window and drag it around the screen. Focus your sight on the window icons (minimize/maximize/close).

OBSERVED RESULT
The animation looks weird around the window buttons, as if it had too few frames per second fitted into the same time window as the rest, while other window parts (such as horizontal borders and corners) look smooth.

EXPECTED RESULT
Should look smooth all around the window, like in earlier versions.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.21.5
KDE Frameworks Version: 5.86.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION