The money is going to one place in particular. Anti-cheating is the most expensive system World Chess operates — detection, engineering, the team behind investigations — and demand for tougher enforcement has climbed sharply over the past year. Ad revenue helps pay for it.
Ads run only after a game, never during play, and only on free accounts. PRO doesn't see them. It's a test for now; a wider rollout depends on how it performs.