Lighting: Before vs. After?

After I build, the lighting gets much darker.
I don’t know why?

The scene is with the PostProcessVolume fully raytraced in GI, Reflections, AO and Translucency.
However, the lamp only has glossy reflection (roughness).

No matter if I switch the Lighting Quality from Preview to Production.
The dark result is the same.

What am I missing here?

Thank you so much for any little help!