It does look like a bug to me but I’m not 100% sure.
I’ve been importing a gltf file exported from 3dsmax. Everything looks great as long as I leave the materials exported from 3dsmax (are these by default pbr materials btw?).
If I create a new pbr material it seems like the faces get flipped.
I tried with a few examples in the playground and get the same behavior.
Let me know what you think.