I am pretty sure this is a bug or at least a feature they forgot to fix before the early access release. Trying to disable the auto exposure in project settings does nothing at all, but disabling it in the viewport works.
Problem is if you’re working on a project where you don’t want auto exposure at all, there is no way of turning it off. Building the project and launching it, you’ll still have the auto exposure in the project even though it’s turned off since the viewport solution is only in the editor.
Doing the post process solution works, but adds to perfomance since the computer has to still calculate it. So in my eyes that is only a temporary solution until Epic has fixed this. Hopefully this will be patched soon.