We are optimizing the memory usage of our game but noticed that TerrainNormalMap is around 85.4 MB. Is there any way to compress this on more lower end platforms?
Not easily. If you are not using Terrain Instancing, Unity will not generate the normal data, and you can generate it yourself and pass it to a custom shader to render - but then you lose instancing. Ideally, Unity would have some kind of “Terrain is Static” flag, which makes the promise that terrain won’t be edited at runtime, and then it could compress all the splat maps and normal maps, which would save significant memory. (I have ways to compress the splat maps in MicroSplat by removing them from the terrain and using external ones, but you can’t easily do that for the height/normal textures).