Hey Desmond,
thanks for taking time to look into this ! Here's another link with a simplified version of my project as it was without your feedbacks :
https://we.tl/t-H3TEGv1YOOI tried chanching the model shading to smoothing angle, and as it did change a bit my shading, it didn't reduce the effect that much.
The rest of what you did was for the much part similar to what I already did, except for the colorspace of the speculars maps (mine are interpreted as SRGB) and the ior values, but trying to adapt my settings to match yours didn't affect the issue..
Once again, thank you very much for the help provided

I'll keep digging and let you know if I find anything
*EDIT :
Hey, the issue comes from the settings of my specular, mine was at 100% where yours was at 10%. I don't see them changing the default value on the video explaining the substance to clarisse workflow, I though all the information were in the map..