Lighting is distorted when I add Diffuse BSDF node

I’m trying to follow a tutorial here: At 24.18 minutes into the tutorial he shows how to add a diffuse BSDF node to get more realistic textures and lighting. When I add the Diffuse BSDF I get some distorted lighting/texturing on the baseboards of my hallway.

Can someone tell me what I am doing wrong?

Blender file

The problem is that the texture is not alligned up 100%. When you use emission, you don’t see it good that the texture are not alligned. But when you switch over to diffuse and the light is going to interact with the geometry you start to see it.

You can reduce the effect by going in Rendered view instead of viewport shading and position a pointlight there where you see the problem not that good. But that’s also not what you want. Best is to get the texture perfect.

This was the best I could get in Rendered view, point light, as desribed above:
So that is with the diffuse shader, camera’s the same position etc. All I changed was: to rendered view, get a point light and position it that you don’t see it. (Again, it’s not a solution, and solution is to get texture alligned correct).

Thanks. At least I know where the problem is. I don’t understand what you did with the point light in rendered view. But I will redo the whole procedure with the FSpy add-on as described in the tutorial. I had already done this successfully, but there was an unrelated problem I wanted to correct (glaring light coming through the door’s window).