But they are also using LOD... as per your article [0]. So it's quite possible (you have the source, go look) that they call this lib with the vertex buffer of the mesh in question and get back an LOD3 mesh that's decimated and simplified but with the projected UV's. This is kinda how Unity wants folks to do "AAA" in Unity. Use a high resolution model and decimate LOD's in real-time like Unreal Engine does. Only, it doesn't work half the time. It requires that the original high poly mesh be properly UV wrapped and not vertex shaded. So to further throw gas on the fire. It's entirely possible instaLOD is the source of a lot of these issues. Combined with what you found in the rendering stages.
InstaLOD is only used in the asset pipeline. I haven't seen any references to real-time use. Haven't found any evidence of real-time decimation either.
To be clear there are LODs, but only for some of the meshes.
[0] https://instalod.com/