Shoutout to FreeCAD having silly rendering issues around transparency. That's literally my desktop wallpaper (default wallpaper in recent version of kde/plasma) shining through the window.

edit: this might be a kde bug, see https://critter.cafe/@irina/116238645215664128  

edit2: and to make myself clear: this is not intended as criticism of either freecad or kde/plasma. it brought me some joy, especially in this particular instance

edit3: the issue seems to go away entirely if I disable wobbly windows in desktop effects in kde

#Freecad #kde