Google is pushing ahead with plans to change Chrome’s extension system that would stop current ad blockers from working efficiently, and has now confirmed a timeline for the rollout, Forbes reports. The the first public version, earmarked as a developer preview, will arrive in July or August, the report said, citing Ghacks. It said Chromium developer advocate Simeon Vincent confirmed this.

Google had proposed the changes – called Manifest V3 – back in January. Last month, despite a furious backlash from users, Google stood firm, saying that current ad blocking capabilities would be restricted to enterprise users once Manifest V3 kicked in. One of Google’s arguments for the change was that content blockers could slow down the Chrome browser the company has not provided any proof of this, Ghacks said, pointing to a benchmark that “for the most part” refuted the company’s claim. Google also claims that the new API will improve privacy and security. While there will still be adblockers for Chrome after Manifest V3, a limit of 30,000 network filters will make even those less capable than before, Ghacks said.

However, it will probably be a while before the changes come to the stable version of Chrome. The soonest it could be available more widely is probably early 2020, the Forbes report said, adding that many Chrome users are already starting to switch to different Chromium-based browsers or Firefox. Microsoft is currently asking users of its Edge browser whether they want built-in ad blockers, while Brave and Opera have already said they won’t be taking on the Manifest V3 changes.

What will Manifest V3 do?

Manifest V3 will see a major transformation to Chrome extensions, including a revamp of the permissions system, the Forbes report says. It will mean modern ad blockers such as uBlock Origin – which uses Chrome’s webRequest API to block ads before they’re downloaded – won’t work. Other extensions such as Tampermonkey, the popular userscript manager, will also be affected.