This is just an FYI and I might be wrong.
It appears that WebGPU is not observing the scene.environmentRotation
while it did observe scene.backgroundRotation
.
I did try this with the Damaged Helmet model and the same equirectangular texture in my GLTF Viewer and GLTF WebGPU and the reflections on the helmet were not the same. The GLTF Viewer did show it as I would expect to see it while GLTF WebGPU was showing it always the same for different values of rotation.
I would suggest you try it in whatever viewer works for you and with your model and whatever texture might provide distinguishable reflection.
It could also be my code and approach that caused this.