try to do it this way:
vetex normals on the borders of uv must be splited,
and the normal map is re-baked for new vertex normals,
at import to recalculate normals MikkTspace.
if you enable the display of vertex normals in the editor, you will see that they are splited at the UVseams, this is a rendering feature, and this should be taken into account by 3d artists.