Google will shut down Manifest V2 in June 2024 and transition to Manifest V3, the latest version of the Chrome extension specification.

Manifest V2 is the older model, no longer accepted by the Chrome Web Store, while Manifest V3 is supported in Chrome 88 or later and will become the standard after the transition.

Ad blockers, a popular type of browser extension, work with block lists (rulesets), and the transition aims to "improve" content filtering.

Google initially planned limits on static rulesets for extensions but has made compromises, allowing 50 extensions simultaneously and 100 in total, with up to 30,000 dynamically added rules.

The transition, despite Google's claims of improved privacy, security, and performance, is criticized by the Electronic Frontier Foundation (EFF) as deceitful and threatening.

Manifest V3 imposes limits on filtering rulesets, including restrictions on filtering based on response headers or URL in the address bar, affecting the capabilities of ad blockers and privacy-protective tracker blockers.

Google's control over both the dominant web browser and a major internet advertising network is seen as a conflict of interest by the EFF.

The transition may limit Chrome users to light ad blocker functionality, prompting some to switch to non-limited browsers like Firefox.

Firefox plans to adopt Manifest V3 for cross-browser compatibility despite concerns.

Google Chrome Enterprise users with a specific policy turned on will have an extra year of Manifest V2 compatibility.