Check the properties of the part that has the weird shadow. Check if it has shadows on. If this doesn’t work maybe try to look for anything interfering with the shadow, such as a misplaced part.
(I’m not fully sure what is in the picture, so sorry if this isn’t help)
I fixed it. Replace every light. Oh this will take some brain power to replace.
Edit: The sun shadows do this too but i can fix that. A resolution slider would be nice.