Chrome’s “Manifest V3” plan to limit ad blocking extensions is overdue

Chrome’s “Manifest V3” plan to limit ad blocking extensions is overdue

Chrome’s “Manifest V3” plan to limit ad blocking extensions is overdue


For several years now, Google has wanted to do away with Chrome’s current extension system in favor of a more limited one, creating more restrictions on the filtering of extensions that block ads and/or work to preserve user privacy. The new extension system, called “Manifest V3”, technically hit the stable channel in January 2021, but Chrome still supports the older and more powerful system, Manifest V2. The first steps toward shutting down Manifest V2 were supposed to start in January 2023, but as 9to5Google first noted, Google now says it has delayed the mandatory switch to Manifest V3 and won’t even have a new timeline for a shut down. V2 ready until March.

The old timeline started in January 2023, when beta versions of Chrome would start running “experiments” that disable Manifest V2. This would move to the stable release in June, with the Chrome Web Store banning Manifest V2 extensions in January 2024. The new timeline is that there is no timeline and each step is now listed as “delayed” or “under review “.

In a post about the delay, Chrome Extension Developer Advocate Simeon Vincent says, “We’ve heard your feedback on the common challenges posed by migration, especially the inability of the support worker to use DOM features and the current hard limit on service extension worker lifetime. We are mitigating the former with the Offscreen Documents API (added in Chrome 109) and are actively looking for a fix for the latter.” After adding that every step of the timeline is suspended, Vincent said, “Expect to hear more about the updated plan and phase-out schedule by March 2023.”

Google’s statement addresses only the second controversial change to Manifest V3: disabling an extension’s ability to launch a background page that is hidden due to background processing. Google wants all background processing to happen in service workers, but this is a complicated environment compared to normal web development and has far more limitations. Google’s delay is only about trying to fix some of these limitations in the background.

The new Manifest V3 timeline, which just says everything is late.
Zoom in / The new Manifest V3 timeline, which just says everything is late.


Google’s post doesn’t mention the additional filters, so it doesn’t look like the world’s largest ad company is changing its mind about ad blockers. The big problem for these extensions is the killing of the “WebRequest API”, which allows ad blockers and other filtering tools to modify Chrome’s network requests on the fly. Usually, this is used to create huge lists of websites (ad servers) that extensions want to block access to. Google has somewhat thrown a bone on these extensions by creating a new API that allows for a limited URL blocking list, but this is only a static list of 30,000 URLs, whereas a typical uBlock Origin install comes with 300,000 filtering rules dynamic. Some ad blockers will try to abide by these rules with Manifest V3, but Google will erode their effectiveness and doesn’t want to implement any of the common sense fixes that would allow them to continue to function at their current level.

“Deceitful and threatening”

Google started this mess in 2018 with a blog post outlining a plan for “Trusted Chrome Extensions, By Default.” As part of the Manifest V3 launch, Google’s official story is that it wanted to reduce the “overly broad access” given to extensions, and that a more limited extension platform would “enable better performing extensions”. The fun side effect of all this is a more limited ad blocker, which would conveniently help Google’s bottom line. The old timeline would have long last implemented the full transition of Manifest V3 six years after this initial blog post, but now it looks like it will take even longer.

The Electronic Frontier Foundation isn’t buying Google’s sales pitch and called Manifest V3 “deceptive and threatening” about a year ago. The EFF said that Manifest V3 “will limit the capabilities of web extensions, especially those designed to track, modify and process along with the conversation your browser has with the websites you visit.” The privacy group said it “doubtful Mv3 will do much for security, too,” as it only limits filtering of website content, not collection, so malicious extensions could still suck up all your data. Even the EFF says performance isn’t a valid excuse, citing a study showing that downloading and rendering ads degrades browser performance. If Google is concerned about security, they might police the extensions store better.

The Chrome team seems to be in for a breakthrough lately. The group has also refused to block tracking cookies until it can first build a tracking and advertising system into Chrome (this has also been repeatedly delayed). If people get tired of the user-unfriendly changes to Chrome that support Google’s business model, there are alternatives. Some Chromium-based forks like Brave and Vivaldi have made a commitment to keep Manifest V2 running when Google disables it. Of course, there’s also always Firefox, which says it will move to Manifest V3 alongside Google, but it will re-add the WebRequest API that filtering add-ons rely on.

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