I think this is on purpose… to have more field of view when shooting. If this bothers you, go into the settings and see what you can do. The answer is probably in the camera settings. I recommend seeing what your mods do, by the way.
It might be a mod or a setting. Third person has wider FOV anyways but it usually matches somewhat with first person. If you mean like you're in FP, switch to TP, and the game is stretched to unplayable then that is 100% a mod.
