Google is continuing its transition to Manifest V3, a new extension framework for Chrome that is gradually disabling older ad-blocking extensions and replacing them with a more restrictive system.
The move has sparked criticism from privacy advocates, developers and users who argue that the changes will weaken the effectiveness of ad blockers and give Google's advertising business greater influence over how content is filtered online.
The transition marks one of the most significant changes to the Chrome extension ecosystem in years, affecting millions of users who rely on browser extensions to block advertisements, trackers and malicious content.
What is changing?
At the centre of the controversy is Google's decision to phase out Manifest V2, the extension platform that many popular ad blockers have relied on for years.
Under Manifest V2, ad blockers could use a powerful API known as "webRequest" to inspect and filter network traffic in real time. This allowed extensions to analyse requests before they loaded and decide whether to block advertisements, trackers, malware or other unwanted content.
Now in Manifest V3, this replaces much of this functionality with a more limited system called "declarativeNetRequest".
Instead of directly inspecting traffic, extensions must provide Chrome with a predefined list of filtering rules that the browser applies on their behalf. Critics argue that this fundamentally changes how ad blockers operate.
Rather than actively analysing web traffic, extensions must rely on Google's browser to enforce filtering decisions using a limited set of rules. Developers say this reduces flexibility and makes it harder to respond to new advertising techniques and tracking methods.
The transition has already affected several well-known ad-blocking tools.
Popular extensions built around Manifest V2 are being disabled or removed from Chrome, forcing users to switch to Manifest V3-compatible versions. While some developers have adapted their products to the new framework, others argue that key functionality has been lost.
The developers behind uBlock Origin, one of the world's most widely used ad blockers, have repeatedly warned that the Chrome version operating under Manifest V3 offers fewer capabilities than the original extension.
As a result, users may encounter more advertisements, sponsored content and tracking scripts than they would under the older system.
Google has, however, countered that Manifest V3 still supports effective content blocking while improving browser security and performance. It maintains that the changes are primarily motivated by security and privacy concerns.
According to the company, the older webRequest API gave extensions extensive access to browsing activity, creating potential privacy risks if malicious extensions misused user data.
They say by limiting direct access to network traffic, Manifest V3 reduces opportunities for abuse while making Chrome more efficient.
Google has further rejected claims that the changes are intended to protect its advertising business.
However, critics remain sceptical. Privacy advocates point out that Google's parent company generates the majority of its revenue from digital advertising; as a result, some observers question whether limiting ad-blocking technology creates an inherent conflict of interest.
For most Chrome users, the immediate effect may be subtle.
Many ad blockers will continue functioning under Manifest V3, though potentially with reduced effectiveness in certain situations.
Over time, however, users may notice more advertisements appearing on websites, less effective tracker blocking and fewer options for highly customised content filtering.
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