The updated Firefox 109 browser, which was released the day before, received support for the new generation Manifest V3 extensions by default - this system caused a sharp negative reaction when Google announced its intention to implement it in Chrome, because it could stop ad blockers from working. However, Mozilla said that now there is no such threat.

The Manifest Version 3 specification was implemented in Firefox in order to support developers creating extensions for Chrome as well. But it's too early to rejoice: although Mozilla's implementation was added to improve compatibility, it differs from Google's version in "some critical areas", mainly related to security and privacy. These areas were also mentioned by Google in 2021 when they added support for Manifest V3 to Chrome, but some of the functions responsible for blocking network requests were broken - they were used by extensions that block ads and trackers. Mozilla offered a compromise, keeping this feature working, but still providing support for Manifest V3 so that developers could continue to create multi-platform extensions.

Google, after criticism from users, decided to postpone the shutdown of Manifest V2, which was originally planned as early as January, and then was supposed to happen in the coming summer - now the deadlines for abandoning the obsolete standard are not indicated.

Another innovation in Firefox 109 was additional extension control tools: the user was able to see a list of extensions that have access to a particular page, and manage them individually, if supported by the extensions themselves.