> Google says FLoC is privacy preserving compared to sending third-party cookies. But this is a misleading baseline to compare against. Many browsers don’t send third-party cookies at all; Brave hasn’t ever. Saying a new Chrome feature is privacy-improving only when compared to status-quo Chrome (the most privacy-harming popular browser on the market), is misleading, self-serving, and a further reason for users to run away from Chrome.
Most regular users wont install a blocker. But most other browsers block 3rd party cookies by default. Meaning, Chrome's market share will be the only reason FLoC will ever succeed. On top of that Chrome is known to shift the goal posts for blockers. You shouldn't be surprised if FLoC cannot be blocked on Chrome in the future.
The floc is based on your browsing history. It is sort of a hash of the sites you visited and can be requested via a Js call by any (!) site you visit.
The floc is shared by a group of users not sure how that works but it is stated that those are a few 1000 large.
Combine that with other tracking stuff like fingerprinting and ip and you can easily identify a user (especially if you are google and your adds hang around everywhere in the net).