Why am I getting these lines?

Hey everyone, I’m trying to see if I can get some help on this issue. I don’t know if anyone else has had this issue, or if you know how to fix it? I’m getting these lines on the walls, but only where the top of the step is.

My guess is that it may be wall direction… Inner/Outer vs Outer/Inner… Or potentially over extrusion on either the top or bottom layers for each of the top and bottom shell/paint layers.