[SUPPORT] ArchViz Explorer

Hi! I have a problem, where in SectionView mode, the shadows inside the building, when looking in the direction of the sun, is too dark, and it looks really bad. I tried to solve this, but found no solution yet, does anyone know what causes this?
I tried a lot of things, this seems to be a problem with the mesh, but I have no idea how to fix it.
Thanks in advance!