I have the "Line" Between the mesh when I add normal map, I think I have try recalculate normal, . Check the dimension of texture. But still got issue : r/blender
Workaround) [Blender 2.8] How to edit a split vertex normal without affecting others? — polycount
How To Identify Normals In Blender 3D? – blender base camp
How to recalculate normals? - Blender Stack Exchange
Exporting Blender model in unity project - Stack Overflow