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

So I just noticed another silly thing about this whole screenshot stuff. If you look closely, you'll notice that the screenshot has an alpha layer. WTAF. (your instance may have re-encoded this picture lossily)

bye bye. you will be missed 

edit: or nvm, it happened again.

So, it's a Qt bug? https://github.com/FreeCAD/FreeCAD/commit/cb8c193408b82e208504f22fa75aa0a4609b00cb

(freecad.overrideAttrs (o: {
patches = (o.patches or []) ++ [
# Fix transparency issues; see https://is-a.cat/@ar/116238609907729115
(fetchpatch {
url = "https://github.com/FreeCAD/FreeCAD/commit/cb8c193408b82e208504f22fa75aa0a4609b00cb.patch?full_index=1";
hash = "sha256-e4Ki1zGZveEMXCxXwgwbd9f2KTJi648M9WIc1Vn9YQM=";
})
];
}))
@ar wait was that the cause?
@natty I can't trigger it anymore with it disabled.