Shadow issue problem.

Hello community hope you are having a great day.
I am having this really weird problem.
please check my attached image.


Do you have any ideas why this happends?

is this realtime or baked lighting?
if you are using static (baked) lighting try turning up lightmap resolution on the big squares plane

This could also be due to the angle of the directional light, try playing around with that and seeing if it changes.