4.19.2 Different Brightness with Volumetric Fog. Viewport vs Play in Viewport

I setup a pretty basic scene to test Volumetric Fog. When I hit play the scene becomes much brighter. This seems to be caused by the volumetric fog. It doesn’ t happen when I delete the fog. The autoexposure is set to a fixed value. Attached are two screenshots.

Try putting in a sphere capture and rebuilding lighting because it’s most likely your skylight.