Each browser is assigned a single floc ID, which is (for now) a 50-bit hash that is not human readable on its own. But the floc ID is intended to capture something meaningful about browsing behavior. Two users with similar browsing history are likely to have similar, if not the same, floc IDs. Floc IDs which are close together (hamming distance-wise) also reflect similar browsing histories. (http://matpalm.com/resemblance/simhash/)

It will be totally possible to gather data about what kind of people belong to a particular floc -- provided that you operate a large website or ad network. It will probably not be possible for normal people.

There's a risk that advertisers will learn that a particular floc ID corresponds to a "sensitive category" of users. That's what google is trying to prevent.

Google plans to audit floc IDs for correlation with visits to sensitive websites. In order to do so, it's assigning a "sensitivity" label to certain websites, and then applying that label to each user who visits those websites. Then it will run analyses to see whether users with a particular floc ID are more likely to have a particular label. Floc IDs that correlate too strongly with a particluar label will be thrown out.

The passage is attempting to explain why this does not prevent adtech from learning other meaningful things about flocs -- for example, that users in a specific floc are disproportionately female, or Muslim, or suffering from depression.

As for whether FLoC is in chrome, see the origin trial page here: https://developer.chrome.com/origintrials/#/view_trial/21392...