Google’s legal defeat at the hands of Fortnite maker Epic Games threatens to roil an app store duopoly with Apple that generates close to $200 billion a year, and dictates how billions of consumers use mobile devices.

The loss — handed down by a San Francisco jury on Monday — is a blow to the two companies’ business model in apps, where they charge commissions of as much as 30% to software developers who typically have few other options.

Epic has spent years railing against the practice, and got a federal jury to agree that Alphabet’s Google unit had acted unfairly as a monopoly. The case is likely to accelerate the weakening of app store rules, which have already come under fire from regulators and lawmakers around the world.