I've got two meshes, one of a male model and one of a female model, they're both using sets of 512x512 images and the exact same export settings (most importantly including normals + tangents, and shape key normals + shape key tangents).
The problem I'm having is the male model is weirdly showing the triangles of the base mesh as very sharp edges but the female model is not. Both models are using autosmooth with a threshold of 90 degrees and the geometry in those areas is far below that angle.
The female model shows these triangles if I dont include the tangents, but they disappear when I include them.
The male model shows them regardless of whether the tangents are included or not.
I've tried turning the tris in those areas into quads and adding supporting geometry, but they still appear as sharp triangles when viewed outside blender.
I'm out of ideas for where to look next for how to solve this problem so I'd really appreciate any direction anyone could give me for somewhere else to look.
Unfortunately I can't actually share the models or textures because I'm under contract so hopefully there's just some advice I can follow.