I believe the change from the current World Ambient Occlusion panel to the new Fast GI panel committed here: rB75704091fccb introduces a confusing workflow when working with the Ambient Occlusion pass.
As of now in 2.93, to tweak the AO render pass, we can preview it in the rendered viewport, and change the distance under: World - Ambient Occlusion - Distance.
This panel has been removed in 3.0. Instead, to tweak the Ambient Occlusion pass distance, we now have to go under: Light Paths, Fast GI approximation.
This change is confusing in my opinion. How can an user assume that to change the distance of the Ambient occlusion pass, he has to go under: light paths - fast GI approximation and change the value of a slider that is greyed out?
Let me know if I am missing something.