Alphabet’s Google said on Thursday it will begin testing a new feature on its Chrome browser as part of a plan to ban third-party cookies that advertisers use to track consumers.

The search giant is set to roll out the feature, called Tracking Protection, on Jan. 4 to 1% of Chrome users globally. It will restrict cross-site tracking by default.

Google plans to completely phase out the use of third-party cookies for users in the second half of 2024.

The timeline, however, is subject to addressing antitrust concerns raised by UK’s Competition and Markets Authority (CMA), Google said.

The CMA has been investigating Google’s plan to cut support for some cookies in Chrome, because the watchdog is worried it will impede competition in digital advertising, as well as keeping an eye on the company’s biggest moneymaking segment, advertising.

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Cookies are special files that allow websites and advertisers to identify individual web surfers and track their browsing habits.

The European Union antitrust chief Margrethe Vestager also said in June that the agency’s investigations into Google’s introduction of tools to block third-party cookies — part of the company’s “Privacy Sandbox” initiative — would continue.

Advertisers have said the loss of cookies in the world’s most popular browser will limit their ability to collect information for personalizing ads and make them dependent on Google’s user databases.

Brokerage BofA Global Research said in a note on Thursday that phasing out of cookies will give more power to media agencies, especially those that are capable of providing proprietary insights at scale to advertisers.