How specular maps work in Fallout 76?

[Arkhaden]

I've been tinkering fallout 76 ini files to fix a graphic issue that my old video card isn't able to handle. The faces of players and myself look really rugged with pixelated shades of light and shadow all over their faces. I reduced the face textures resolution in order to fix the issue.

 

And it work but the result is a very low quality faces in game. But what I realize is that I just simply reduce the face resolution to match the size of some specular effect in the faces. This is something never happened in fallout 4. I believe that some how could be a shade effect or specular map is way below the 1024 resolution. So in order to fix my issue I reduce the resolution of the texture. Or perhaps there is some new shading effect implemented in Fallout 76 like for example the "fake character lights from Fo4". In this case it seems that this effect only applies to the face texture and nothing else in the game. I wonder if is possible to thinker with that. Does anyone know any new face light effect that can be toggle in the ini files? Or how to tinker with the specular maps? It could be that the specular maps run diferent in FO76.