A class action lawsuit was filed against Roblox this week alleging that the gaming platform has facilitated illegal child gambling.

The suit was filed in the Northern District of California last week by two mothers to claim their children have gambled on third-party sites using Roblox currency.

According to their parents, Rachel Colvin and Danielle Sass, the children have lost “thousands” in Roblox gambling on the sites without the knowledge or permission of their parents. For some perspective, 800 Roblox runs $9.99 on the Roblox website.

First reported by Bloomberg Law, beyond Roblox itself, the suit names Bloxflip, RBLXWild, and RBXFlip as businesses running illegal gambling operations that specifically target children. While the gambling sites use Roblox currency they are not affiliated with Roblox, children are instead connecting their digital wallets from Roblox to these third-party sites where they can play games like roulette to win or lose the virtual currency.

The plaintiffs argue that Roblox could have prohibited or stopped the gambling websites from running and targeting children, who make up a good deal of Roblox users.

“Children, who previously could not access the funds to participate in online gambling, now have, collectively, billions of Robux at their disposal,” Colvin and Sass said in the suit.

Roblox earns a 30% fee on transactions using Roblox, including those that occur on gambling sites. So, while the company is not directly involved in gambling sites, it is profiting from them.

The suit comes at a time when Roblox is already under fire for how it handles advertising to children. In May, the Children’s Advertising Unit of the nonprofit BBB National Programs found that Roblox didn’t make it clear to children when they were seeing ads versus when they were viewing content on the platform. The watchdog group Truth in Advertising also filed a complaint with the FTC regarding the service last year.