What would cause a decal on character body to have shadowing issues along the uv seams?

Imagine you stamp decals on your 3d character in unreal engine. But if you stamp your decal over a UV seam, the decal looks good on one side of the uv seam, but on the other uv side, it’s shadowed and dark.

How do you fix issues like this? Is it the decal normal map that’s the problem?

When applying decals in real time you can have depth that may be placing the decal too far away or too close to the object in question and could definitely cause artifacts such as this. Have you tried manipulating the sizes and locations of where they are applied?