When running freedroidrpg with "performance tweaks" -> "show light radius"=yes, the graphic flickers between good image and an image with wrong light and shadows.
It is imho a minor bug but should be documented to help people.
Created attachment 756761 [details]
with light radius the graphic flickers, broken state
Created attachment 756764 [details]
without light radius, the graphic flickers, state is normal
Created attachment 756767 [details]
light radius=no, the graphic is OK