As far as I can tell, you could, and will still be able to, make ads invisible based on dynamic data, but under Manifest v3 you would not be able to prevent the

As far as I can tell, you could, and will still be able to, make ads invisible based on dynamic data, but under Manifest v3 you would not be able to prevent the ads from downloading (and sharing private information, including your FLOC cohorts) based on dynamic heuristics, because Manifest v3 makes it impossible to use anything other than a simple, limited-length blocklist to prevent a network request from being made. See: https://developer.chrome.com/docs/extensions/mv3/intro/mv3-overview/#network-request-modification https://developer.chrome.com/docs/extensions/mv3/intro/mv3-o... It's a decrease in privacy being sold as an improvement in security and performance. Could they have instead implemented a persistent super-sandbox for network-blocking heuristic code that addresses the performance and security issues, while still enabling dynamic network blocking? Probably! But why would they, when the primary use case is heuristic-based ad blocking? And I suppose you're right - part of any defense in depth is reducing the number of first-level successes. And it's very possible it was script kiddies who sold the cookies to the actual attackers in the EA case. But there's more going on here than just security.