Hi @5DRealities,
That sounds like expected behavior. CesiumUnlitTilesetShader doesn’t generate normals since we can take advantage of the Unlit rendering mode in Unity. But I think you can use CesiumDefaultTilesetShader to cause normals to be generated for Google Photorealistic 3D Tiles. If you disable Generate Smooth Normals, the resulting normals that get generated should be flat.
(Definitely let us know if this doesn’t work – after switching environments, I don’t have Unity set up yet to try this myself. 
)