Very likely it's the normal map. It's probably at blue up. Go to the material and turn the normal off, see if the issue goes.
If so, changing the channel / adjusting it down might help. Otherwise, load it up in blender and reexport it y up.
If not, do the same with all the other textures one at a time.
One more thing to check is that you don't have the roughness plugged into the albedo or similar. Check there aren't multiple passes. If it's still not fixed, make a fresh material and plug the textures in manually. Finally, just view the textures in photoshop/gimp - it might give you a clue.