The Ad Blocker You Chose is Being Removed for You

On 31 August 2026, the Chrome Web Store removes the last extensions built on Manifest V2, the older rulebook that governed what a Chrome extension was allowed to do. A week earlier, on 7 August, Microsoft announced that Edge is following the same path: the consumer transition starts this month and should be complete by the end of the year, with enterprise customers following in early 2027.

Six days after the Chrome deadline, on 6 September, the next Digital Independence Day (DI.DAY) takes place. The timing is a coincidence. The lesson is not.

What actually changed

A browser extension is a small program that a user installs to change how their browser behaves. Content blockers — the category that includes ad blockers — are among the most widely installed of these.

Manifest V2 gave extensions the webRequest interface, which let a blocker inspect each network request as it happened and decide, in that moment, whether to allow it. Manifest V3 replaces this with declarativeNetRequest: the extension submits a list of rules to the browser in advance, and the browser applies them. The extension no longer sees the traffic.

The practical difference is not subtle. A declarative rule cannot react to what a page is doing right now, cannot be based on the content of a server’s response, and cannot express several of the conditions that blocklist maintainers rely on. This is why the full version of uBlock Origin — the most widely used open-source content blocker — cannot be shipped for Chrome.

Its author, Raymond Hill, maintains a reduced replacement called uBlock Origin Lite, and documents its limits candidly: Lite is, in his words, “not meant as an MV3-compliant version” of the original — MV3 being the shorthand for Manifest V3 — and users are told to pick a replacement deliberately rather than assume Lite is it. Notably, the rule-count ceiling is not the binding constraint he identifies. Two others matter more. Filters that depend on inspecting a response cannot be translated at all. And because the rules are compiled into the extension package, updated blocklists reach users only when a new version of the extension ships — which means they pass through the store owner’s review process on the way.

The case for Manifest V3, and the problem with it

Google’s stated reasons deserve a fair hearing. An extension with live access to every request a browser makes is a serious piece of attack surface. Extensions have been sold to new owners and quietly turned into trackers or malware; a permission model that grants less power by default genuinely reduces that risk. Manifest V3 also bans remotely hosted code, which closes a real avenue for an extension to change its behaviour after review. Microsoft notes that 95% of the most-used extensions in its store had already migrated. For most extensions, this is a straightforward security improvement.

The objection is narrower and harder to dismiss. Google’s revenue comes overwhelmingly from advertising. It is the company deciding what the world’s most-used browser permits ad blockers to do. Even if every engineering judgement behind Manifest V3 is made in good faith, the decision was taken by a party with a direct financial interest in the outcome, without any process by which affected users could contest it. That structure is the problem, independently of the merits of any individual choice.

Not every browser vendor reached the same conclusion. Mozilla decided to support both webRequest and declarativeNetRequest in Firefox, arguing that the declarative approach as designed does not cover everything content blockers need. Brave, built on the same Chromium foundations as Chrome, kept full blocking working as well. The same technical constraints produced different answers — which shows these were choices, not necessities.

Why defaults decide this

The common response is that anyone who cares can switch browsers. This underestimates how the outcome is actually determined.

Browsers arrive pre-installed. They are the default on a work laptop, on a school device, on a phone handed over at the shop. Switching means moving bookmarks and saved logins, relearning where the settings are, and accepting that an occasional site will misbehave. None of this is hard for a confident user. All of it is enough friction that most people never do it.

So the effective consequence of a Manifest V3 decision is not that users choose a weaker blocker. It is that the large majority get one assigned to them, and the people best placed to notice and respond are the ones with the time and technical confidence to act. Privacy protection distributed that way stops being a right and becomes a hobby.

What can be done on 6 September

Digital Independence Day falls on the first Sunday of every month, and exists precisely for this: a fixed date to make one switch rather than an open-ended intention to improve things.

For this one, the concrete step is the browser.

• Move to a browser that still permits full content blocking. Privacy Guides recommends Firefox as the general-purpose alternative, Brave where Chromium compatibility is needed, and Mullvad Browser for stronger anti-fingerprinting out of the box. DI.DAY’s own overview of browser alternatives covers the same ground.
• Install the full uBlock Origin from the Firefox add-ons store once moved.
• Take one further step while at it. DI.DAY publishes switch recipes with realistic time estimates — search, email, messaging, passwords — and lists local events for those who would rather not do it alone.

Anyone unable to move — a locked-down work machine, an unsupported device — is better served by uBlock Origin Lite than by nothing.

The wider point

The individual fix is available, and worth taking. It is not a substitute for the structural question.

Nearly all browsers now run on one of three engines, and two of them belong to companies whose primary business is advertising or platform services. When a vendor in that position sets the limits on privacy tooling, the result is a private decision with public consequences and no route of appeal. The European Union already regulates gatekeeper conduct through the Digital Markets Act. Whether the terms on which a browser vendor restricts privacy-protecting software belong within that scope is a legitimate question for European regulators — and one that will not be settled by individuals switching browsers on a Sunday.

Both things are true. Switch on 6 September. Then ask why switching was necessary.

Things we can do:

1. raising this issue with Google and the Chromium project;
2. advocating for more flexible Manifest V3 filtering limits;
3. supporting the continued availability of Extended Manifest V3 where appropriate;
4. examining whether browser-platform restrictions on privacy extensions raise questions of competition, interoperability and digital rights in the European Union.