There are no specifications about what the cohorts will be, Google is literally leaving that for the ad companies to figure it out. It wouldnt be suprising it a

There are no specifications about what the cohorts will be, Google is literally leaving that for the ad companies to figure it out. It wouldnt be suprising it at all they realize a way to make small enough cohorts in such a way you can be fingerprinted. The bottom line is that you are giving them your browsing data, obfuscated by fancy algorithms. Unless you trust ad-tech to have the best interests about your privacy (ha!)