Package: kwin-x11 Version: 4:5.21.5-2 Every time I start a new plasma session and kwin launches, it will have a series of graphical glitches which make the session unusable, including: - Not displaying the system taskbar. - Not displaying any part of an application window which reaches the bottom half of a screen. - Having issues with graphical effects such as drawing rounded window borders. - Getting half of the screen in black for a while after issuing a restart command. (Among others)
When this happens and I restart the computer (a simple plasma session restart does not suffice), next time it usually starts with compositing disabled, which allows for kwin to start correctly, and compositing will work fine once I reenable it in that same session, but then the problem will happen again in the next restart. The file ~/.xsession-errors will afterwards show many instances of this line: [2594:2594:0901/114421.740314:ERROR:shared_context_state.cc(73)] Skia shader compilation error (See also https://bugs.kde.org/show_bug.cgi?id=441871 for more details and for the full xsession-errors) I suspect there might be some issue between the current kwin version and the video drivers (this is on an AMD Vega 56 card using the mesa drivers, currently libglx-mesa0==21.2.1-2). The issue is present whether the compositing is set to OpenGL 2.0, OpenGL 3.1, or XRender.
