When playing CS:GO, if you find a loot box, you'll need to pay Valve a real sum of money for a key to unlock said box. But, until now, it's also been possible to buy keys and sell them on to your friends and enemies for a profit. Naturally, it's plausible that such an anonymous system of commerce, even with such small figures, could be used to clean up dirty cash, but Valve haven't backed up its claims with any proof.
This isn't the first time that the title has been associated with some less-than-ethical practices, as well. Back in 2017, a pair of YouTubers directed their fans to visit a CS:GO gambling website, forgetting to disclose that they owned said site.
Users who have purchased CS:GO container keys before Monday 28th October will still be able to be sold on and traded. But from now on, the keys will be stuck with you, and it's likely that the change will impact other in-game currencies that can be sold in a similar fashion. We're also going to keep one eye on the Department of Justice website, since it's likely where Valve goes, the feds will follow.