As of 2020, Google has been testing opting out of cookies in the Chrome browser as part of its Privacy Sandbox initiative. The company plans to implement its new Topics API standard from 2024, which will allow advertisers to target ads based on general topics based on browsing history, rather than collecting cookies. This is said to avoid user identification for ad technology providers.

Third party cookies are small files stored on a user's device that allow advertisers and advertising companies to track users as they browse different sites on the internet. For example, they allow a hotel to target ads to users who have previously visited their website and help advertisers measure the effectiveness of their campaigns. Google offers a more confidential replacement.

But now Google may have to redesign the proposed protocol. Recently, the web standards arm of the World Wide Web Consortium, known as the W3C, asked Google not to continue developing the Topics API in its current form. “The proposed API appears to continue the policy of improper snooping on the web, and we don't want it to evolve further,” wrote Amy Guy of the W3C Technical Architecture Group in a Github post.

Amy also noted that the Topics API allows a third party to process and combine user data to create profiles based on it. This, in turn, can be used to discriminate content, such as the ability to choose which ads to show to user groups based on sensitive and protected characteristics such as a person's race.

Google disagreed with this statement. "We are confident that this API will provide significant privacy improvements over third-party cookies and are continuing to develop it," a Google spokesperson said in a statement.

At the moment, the Topics API has not received support from the developers of the Firefox and Safari browsers. Robin Berjon, head of standards and governance at research firm Protocol Labs and board member of the W3C, says the Topics API has little chance of being adopted in its current form. "No other browser vendor wants this, and the leading authority on web architecture has rejected it," he said.

Other browsers such as Apple Safari and Mozilla Firefox already block third-party cookies as privacy features. Despite objections from the W3C, Google can still go its own way, not least because web standards can take years to develop and the company isn't limited to them. Google has its own commercial priorities and will not be able to opt out of cookies until it provides an adequate substitute for them.

"The Topics API is especially important to Google because it's relatively easy to implement and test," said Alex Cone, co-founder of ad privacy learning platform Coir. “If they find that it is of value to advertisers, they will do it.”