It’s about the last version of Render[IN] downloaded
When the Render preview is open, every kind of action made on parameters, increases the light amount ( ISO parameter) in the scene, and if you continue to render, the product will be like that.
So you have to regenerate the render preview (after even a single change in any parameter) in order to go to the normal lighting (as it is set).
Maybe this is a problem during the process of developing.