Exposure does what it should, brightness however doesn’t. All it does is change the contrast, like, you know, the contrast slider. It’s borderline pointless to have it at anything lower or higher than 50 as all it does is give you that “matte” feeling that many photographers nowadays like. It doesn’t boost shadows, it doesn’t give you more detail in the dark. It simpy doesn’t affect the only thing it’s supposed to. Brightness
If brightness was to be changed to highlights, that only affected the highlights, we could EXPOSE for the dark areas while retaining detail in the highlights. You know, just like in real life.
Source: I do photography irl