State antitrust watchdogs are targeting Google’s plans to phase out third-party tracking cookies, building on a major lawsuit filed last year. The group of 15 attorneys general, led by Texas, updated its complaint about Google yesterday to include a more detailed case against the search giant, including new claims about Google’s strategic use of the Chrome browser. In particular, the new complaint takes aim at recent privacy updates to Chrome, which could better protect users’ personal data while also entrenching Google’s market position.

Filed in December, the Texas complaint is one of three ongoing antitrust cases against Google. That same month, the Colorado attorney general led a group alleging that the company stifled competition by manipulating search results. A separate case from the Department of Justice is focused on Google’s dominance of the web search marketplace and associated ad business.

Like the original Texas complaint, Tuesday’s updated filing primarily focuses on Google’s technology for targeting ads across the web. The attorneys general argue that Google used its power in search, streaming video, and other markets to stamp out independent advertising platforms, forcing small businesses and media outlets to use its system.

But in the updated complaint, the states apply this argument to Google’s “Privacy Sandbox” — a tool that’s supposed to replace invasive third-party tracking cookies with a more limited system devised by Google.

“Google’s new scheme is, in essence, to wall off the entire portion of the internet that consumers access through Google’s Chrome browser,” the complaint reads. Blocking cookies might broadly be a good thing — other browsers like Firefox and Safari have already done it. But Chrome dominates the browser market, and it’s part of a much larger Google product suite. The suit argues that Google’s plans would require advertisers to use it as a middleman and would make Google’s own advertising system far more attractive.

For years, Google has been gradually scaling back its use of tracking cookies, announcing earlier this month that it will not establish an alternate system for tracking users on the web. But critics of the company — including the Electronic Frontier Foundation — have criticized those efforts as self-serving. Now, state regulators seem to be adopting those criticisms and putting new legal pressure on Google’s efforts to block tracking in Chrome.

“Google is trying to hide its true intentions behind a pretext of privacy,” the suit continues. With Privacy Sandbox, “Google does not actually put a stop to user profiling or targeted advertising — it puts Google’s Chrome browser at the center of tracking and targeting.”

Google did not immediately respond to a request for comment.