There’s a new Big Tech antitrust bill in town, and this one is especially painful for Google.

A group of lawmakers led by Sen. Mike Lee (R-UT) introduced the Competition and Transparency in Digital Advertising Act on Thursday. This bipartisan and bicameral legislation would forbid any company with more than $20 billion in digital advertising revenue — that’s Google and Meta, basically — from owning multiple parts of the digital advertising chain. Google would have to choose between being a buyer or a seller or running the ad exchange between the two. It currently owns all three parts, and has been dogged by allegations, which it denies, that it uses that power to unfairly manipulate that market to its own advantage.

“This lack of competition in digital advertising means that monopoly rents are being imposed upon every website that is ad-supported and every company — small, medium, or large — that relies on internet advertising to grow its business,” Sen. Lee said in a statement. “It is essentially a tax on thousands of American businesses, and thus a tax on millions of American consumers.”