A page of random issues i have hit and their fixes
KWin task bar and task switcher previews broke. journalctl showed:
kpipewire_logging: need a window and a context ToolTipDialog(0x55b6d7e76960 exposed, visibility=QWindow::Windowed, flags=QFlags(FramelessWindowHint|WindowStaysOnTopHint|WindowDoesNotAcceptFocus), transientParent=0x55b6d45aeb30, geometry=0,1468 296x195)
The fix was to set SceneGraphBackend=auto in ~/.config/kdeglobals and restart