So i found a fix but its destructive,
i simply destroyed all the lights in my level since adding a camera in the scene would screw it all up.
Remaking the lighting fixed my issue and adding a camera no longer changes the exposure of the whole level, but i sadly didn’t understand what causes it so my questions is still up, as i want to find a way to avoid it / fix it in the future without having to redo a day’s worth of work.