Hi, so i ran into an problem.
I can seem to find out what is causing this weird shading, i did check the normals and such recaculated and flipped them but they don’t seem to go away.
you can find this in the toolbar ( the panel on the left ), you have just applied the smooth shading only to that surface, the rest of the object still is using the flat shading.
I can think 2 cases: or that window is not aligned with the walls around, aka the wall around is not flat, or that walls are set to smooth while the rest of the house is set to flat.