That's because in the first level, the image is stretched, and in the later levels it's actually cropped instead (Vert-), I have no idea why that happens, and I don't know how to fix that. For now, that's the best I can do, maybe someone can make a more comprehensive patch for the game that deals with the issue, and has more skill than I have. I'm sure the rest of the game plays fine with the proper FOV, unless there are later areas where the image becomes stretched again.
Also, that is