In context: Google pitched its Federated Learning of Cohorts (FLoC) tracking technology as a more privacy-respecting alternative to third-party cookies, letting advertisers track user cohorts or groups with similar browsing histories instead of targeting individuals. However, privacy advocates like the Electronic Frontier Foundation and Google's own search-engine rival DuckDuckGo, remain unconvinced by this tracking method, which is currently being tested on Chrome users and could eventually make its way to the Web.

DuckDuckGo has announced that its Chrome browser extension has been updated to block Google's new tracking technology. Although the company suggests users simply stop using Chrome as the most effective way to block FLoC - it's the only browser currently supporting this feature - those looking to continue using Chrome can install DuckDuckGo's extension that now comes with enhanced tracker blocking.

Google's privacy-focused rival says that its own search engine has also been configured to disable FLoC by default; however, the experimental feature was silently turned on for millions of Chrome users in the US, which the Electronic Frontier Foundation has termed a "terrible idea" and a concrete breach of user trust.

Highlighting privacy concerns of this new approach, DuckDuckGo notes that websites and third-party trackers have access to groups' FLoC IDs and IP addresses, which they can use to target ads and content at individuals. Although these IDs are non-descriptive and represented by an "anonymous-looking number," DuckDuckGo says that through FLoC, Google exposes users' derived interests and demographics to websites they visit, using data from detailed profiles that the search giant has built up and maintained over the years.

While FLoC's adoption by advertisers is likely to expand over time as the feature becomes widespread, Google notes it to be 95% as effective as third-party cookies, the tracking mechanism which it plans to make obsolete in Chrome by early 2022.