I am currently facing a problem with my texture. I have created a very simple Object and added some textures to play around with. As you can see in the following screenshot the upper part of the model displays the texture a lot darker than the part below:
Below you can find my node setup. The texture itself was created outside of Blender. The face normals are checked and look like I would expect them to look.
Also nothing special as you can see. The texture itself is created procedurally and does not have any difference in brightness.
Can anyone give me a good hint as to what's going on here? I can really not understand why the upper part is displayed so much darker. I am using Blender 2.91.
The file: https://www.dropbox.com/s/wb6iz1vtmgj0kks/Pillar.blend?dl=0