Try turning off auto exposure in Project Settings if you haven’t done so, and then set min and max brightness to 1 in PostProcessVolume!
Keep in mind, Post Process Volume is an effect that happens AFTER render. It is for changing the scene, only things that are activated on the Post Process Volume affect anything. So in order for it to do anything, the box MUST be enabled! Otherwise it will use default settings which includes bloom and AntiAliasing etc.
