Google's move to Manifest V3, the Chrome extension platform that replaces the older Manifest V2 architecture, reached its final stage in mid-2025 when Chrome 138 disabled Manifest V2 extensions for all users across all release channels, removing even the enterprise policy that had let organizations keep the old extensions running. That cutover ended the run of the full version of uBlock Origin on Chrome, which depended on Manifest V2's more powerful blocking APIs.
A year-plus later, the practical question is how well the Manifest V3 replacements actually work. A test published in August 2026 by SuperchargeBrowser loaded seven Manifest V3 ad blockers into Chrome and measured their performance directly: the two most widely used extensions in the test allowed Google's own ad scripts through by default, while the best performer, uBlock Origin Lite, neutralized all 14 of the test's ad scripts.
Why it matters
Manifest V3 restricts the dynamic, code-injection-style filtering that older ad blockers relied on, replacing it with Chrome's declarativeNetRequest API, which caps the number of blocking rules an extension can apply and limits how blockers can react to new ad-serving patterns in real time. That structural limit is why performance differs so much between extensions built for the new platform — some rely on curated static filter lists that are necessarily less adaptive than the old approach.
Because Chrome remains the dominant desktop and mobile browser, decisions made in its extension platform effectively set the ceiling for what ad-blocking and content-filtering extensions can do across most of the web, regardless of which specific extension a user installs.
How it works
9to5Google's coverage of the transition described Manifest V3 as closing what it called Chrome's "final loophole" for ad blockers still running under old APIs, marking a hard stop for most legacy ad-blocking approaches on the browser. OpsMatters' review of the 2026 ad-blocking landscape found that publishers and streaming platforms have adapted their own anti-ad-block detection in response to the weaker blocking tools now available under Manifest V3.
Not every ad blocker vendor describes the transition as damaging. Adblock Plus published a post noting that it had already adapted to Manifest V3 about two years prior and reported it remained fully operational under the new system, pushing back on narratives that Chrome had effectively killed ad blocking outright.
The competing read
Google has consistently framed Manifest V3 as a security and privacy improvement, arguing that limiting extensions' ability to execute arbitrary remote code reduces the risk of malicious or compromised extensions harvesting user data — a real problem with the old platform. Critics, including ad-blocker developers, counter that the same technical restrictions that limit malicious extensions also happen to limit the browser's most popular category of extensions for blocking Google's own primary revenue source, advertising, and note the restrictions apply unevenly since some sophisticated blockers still perform far better than others under the same API constraints, as the SuperchargeBrowser test demonstrated.
What happens next
With Manifest V2 fully gone and no enterprise policy remaining to revive it, the ad-blocker ecosystem's future on Chrome now depends on incremental improvements to the declarativeNetRequest API and on how aggressively individual extension developers optimize their static filter lists within Chrome's rule-count limits. Users who want the strongest blocking performance available under the new rules will likely need to keep tracking independent comparison testing like SuperchargeBrowser's rather than assume all Manifest V3 ad blockers perform similarly.