https://www.bleepingcomputer.com/news/security/vivaldi-brave-duckduckgo-reject-googles-floc-ad-tracking-tech/

Last month, Google announced plans to roll out a new privacy-focused feature called Federated Learning of Cohorts (FLoC) for the Chrome browser and ad serving websites.

The technology is meant to replace the more traditional third-party cookies used by ad networks and analytics platforms to track users across the web, which can be detrimental to preserving user privacy.