My normal map goes wild on Unreal Engine 4, while on Blender/Marmoset therer's no such thing. The edge looks like this in viewport:
And probably the troublemaker on the texture:
But as I said before, I don't have that problem on different enviroments. Also smuding in Photoshop this area/transition makes no difference.
Turning off "tangent space normal" kinda solves the problem, but makes another artifacts + the model looks so flat that it doesnt need normal map.