I never noticed this seam on my rocks till I decided to modify the main texture for them to emit light from some of the low spots. This is a texture on all 6 sides of a cube, and subdivided a few times.
What methods are available to reduce the visibility of this seam?
Edit: Looks like I use texture painting to do what I need! Only issue is is that some sort of symmetry mode is on where both sides of the seam mirror each other.