When hovering the icon-only task manager after shading a window, instead of the window thumbnail, an icon is shown instead. Even though "Keep window thumbnails" is set to "Always". Minimizing instead of shading works as expected - thumbnail is shown in this case. So it is just for shaded windows that the setting does not work.
Window thumbnails are done by Plasma and not by KWin. Given that reassigning to Plasma.
Shouldn't it be frameworks-plasma instead where the component is?
maybe llvmpipe drivers?