Taskbar- and Menu-Icons missing after update to Hirsute Hippo (21.4)

All Application and window icons are missing/changed to black squares after update to Hirsute Hippo (Kubuntu 21.04)[Desktop with missing icons][1]

Changes in Theme, Iconset, plasma style (Breeze, Oxygen, Kubuntu tried) does not help. In addition, also some buttons in dialog windows are simply straight black, so are the window controls (minimize, close, etc.)

When i try to change an icon of the taskbar via properties, the icon itself is shown in the dialog. Nevertheless, it stays black after changes. Newly updated from Intrepid to hirsute. KDE Plasma 5.21.4.

Found some threads regarding Desktop icons, since here i have problems even with buttons and window controls, i guess its something else... any ideas? [1]: https://i.stack.imgur.com/6Rhb1.jpg

Had the same problem today, found the solution here: https://etbe.coker.com.au/2020/12/04/kde-icons-disappearing-unstable/

TL;DR:

Run

sudo apt remove libqt5quick5-gles