When rotating a loaded gltf cube the quaternion is causing the cube to get distorted.
There seems to be a bug causing the rotation to also scale the cube.
Drag and drop this gltf which is a simple cube with no rotation or position.
the quaternion gets set to 0,0,0,1
Then try spinning the cube with the inspector changing any of the x,y,z parameters and you should see it get all distorted.
cube.gltf.zip (1.3 KB)