This week Google announced that Chrome browser extensions written to comply only with the Manifest V2 specification may no longer function after January 2023.

After that, Chrome will only support extensions that comply with Manifest V3 rules, which may mean the demise of some ad blockers and privacy extensions.

"After years in the making, Manifest V3 is more secure, performs better, and protects privacy better than anything that came before," said David Li, product manager for Chrome extensions and the Chrome Web Store, in a blog post.

"This is an evolution of the extensions platform that takes into account both the changing web environment and the future of browser extensions.

According to Li, after January 17, 2022, three and a half months from now, new Manifest V2 extensions will no longer be accepted in the Chrome Web Store. Developers may release updates to existing Manifest V2 extensions.

In January 2023, Chrome will no longer run any Manifest V2 extensions, and according to Li, Google will share more details as these dates approach. A more detailed timeline can be found here.

Google has stated that the revisions to the Chrome browser's extension framework will address security issues it claimed when Manifest V3 was first introduced in 2019.

That is certainly a legitimate concern. This is because malicious browser extensions have been rampant in the Chrome Web Store over the past few years. Many of the extensions were abusing the privileges they held under Manifest V2 to spy on users and steal sensitive information.

However, some experts are not convinced that this is about user security or privacy.

"Our criticism still stands," Alexei Miagkov, senior staff technologist at the Electronic Frontier Foundation, told The Register.

In 2019, Miagkov was a co-author of an EFF report stating that "Manifesto V3 is a blunt instrument that does little to improve security while severely limiting future innovation."

One widely used browser extension that will likely not work under Manifesto V3 is EFF's own Privacy Badger, which blocks web trackers.

Google's annual report to the U.S. Securities and Exchange Commission (SEC) in early 2019 stated that ad-blocking technology could impact Google's revenue. Google also pays Adblock Plus to whitelist its own online ads, and Adblock Plus appears to be in compliance with Manifesto V3.

Around the same time, Raymond Hill, who maintains the free ad blockers uBlock Origin and uMatrix, posted on Chromium's developer forum that Manifest V3 means his two ad blockers "no longer exist." (Chromium is the open source platform on which Chrome and many other browsers are built.)

Like Hill, some suspect that removing the ad blocker is the real reason for Manifest V3's overhaul of browser extension permissions.

However, Simeon Vincent, a developer advocate for Chrome Extensions, said that in late 2019, Manifest V3 will not disable ad blockers, but rather allow developers to create better ad blockers.

It is unclear how much money Google and publishers are losing because of ad blockers, but the company's claim that Manifest V3 will help developers build better ad blockers seems somewhat unlikely.

Many ad blockers and privacy extensions no longer work on Google Chrome, but it will be interesting to see what happens if rival browsers continue to support them.

Mozilla, the makers of Firefox, have stated that they will support Manifest V3 but will also allow ad blockers to function; Brave is Chromium-based like Edge, but at a deeper level (by default) unaffected by Manifest V3. It states that it will block ads.

According to StatCounter, Chrome now accounts for about two-thirds of the global desktop browser market. All the rest have less than 10%. If Chrome displaces ad blockers and other browsers don't, it could be Chrome's chance to reclaim a larger piece of the pie.