https://www.pcgamer.com/valve-adds-scam-protection-to-steam-trades-following-wave-of-counterfeit-items/

Yesterday we reported on two games being used to pawn counterfeit Steam Community Market items: Abstractism, which was being used to peddle fake Team Fortress 2 items, and Climber, which was doing the same thing but with fake Dota 2 items. Since those scams were discovered, Valve has instituted new trade protections to protect Steam users from scams like these. 

A GitHub archive of the Steam Database (spotted by Reddit user wickedplayer494) shows two warnings which now appear during "suspicious" trades. The first warns players if "one or more of the items you're receiving in this trade come from new games on Steam," which will help filter out slapped-together cash-grabs. However, it's unclear what the cutoff point is for "new games," and in the case of games like Climber, which was on Steam for two months before it was used for item scamming, this warning alone may not be enough.