"Tracking protection" sounds more like "alternative tracking."
Google's Privacy Sandbox initiative, just like its name implies, was designed to be an alternative to cookies that will allow advertisers to serve users ads while also protecting their privacy. It assigns users to groups according to their interests, based on their recent browsing activities, and advertisers can use that information to match them with relevant ads.
Lot of time, money, and effort toward a moderate improvement rather than just not perceiving users as products. But...improvement is improvement.
What's the downside?