Shadow errror in Eevee

Hey guys, I am having trouble figuring out why there are these weird shadows in my render (I´m using Eevee). I tried to recalculate normals and also checked if there were any small gaps between the objects. There weren´t. The walls on the sides had also the same problem but I was able to get rit of those shadows by overlapping the side walls with the other objects - by moving the walls some centimeters on the x-axes. Unfortunately, I am not able to do this with the back wall (the one with the windows) since moving it and also modeling like extra stuff behind it to avoid light doing something to it didn´t solve the issue. Is there a proper explanation of why this shadow-issue happens and is there a way to solve the problem? I also rotated the HDRI map to see if any light sources affect the falloff of the shadows - they did not. So other than a bug in Blender I can´t explain what happened. Do you know why these shadow-issues happen?

I was able to solve the Problem. In the Eevee render settings Ambient Occlusion was ticket which is fine usually. The distance setting was on 1, -> shadows were there. When I decreased the distance setting the shadows were getting smaller until they were totally gone at 0.