Global mods review reports people make everywhere in the general forums. They moderate game hubs by default, but if a developers has their own moderation team, they can opt out of Steam moderation.

Valve, as far as I know, pays a thirdparty company for the global Steam forum moderation.

Originally posted by ᴋoa:

I would like to know how it works, if most are real people, and if said people work for valve, depending on the community.

https://www.valvesoftware.com/en/

Have at it, we do not work at Valve so anything we tell you will simply be speculation.