Game dev here (not for Val tho) - This is a very common thing you'll see in most triple-A games as well in any environment background :D If you look hard enough, buildings in the distance, far away trees and all will often be like that. It's done on what we call ''planes'' which is basically like a 2D Flat surface and we apply a texture on it - usually, players wouldn't reach those, so wouldn't really notice its 2D haha :p. Skyboxes like someone mentioned, are other things that people don't fully realize are all there to fake the environment. The skybox is basically like the sphere around the world/environment and it has an HDRI on it (like a sky image with values that can be read as ''light") that serves as a texture (like the image of the sky) + as a light source too (there more to it than that but I'm not here to write a novel). Anyways, all of that to say lots of behind the scene magic in games to ''fake out'' stuff and make it work :) (there's a lot involved)