i'm working on a project but i get a strange issue with the 3d model. For some reason, "reflexion" flip on some faces as soon as I put alpha lower than 1.0.

I tried to delete the face then fill -> worked for somes I checked face orientations and normals -> they are all identical I asked some AIs to find some answers but nothing worked (UV project, flip face, add tangent to material, delete item datas...).

On the attached screen cap, face orientation & normales are On, and the principled BDSF has alpha set to .999

I'm pretty sure it's a model problem, because I made an GLTF export to threejs, replaced the material by a threejs native one, and I have reflexion issues at this faces.

What could it be, and how to fix it?