The U.S. Department of the Treasury’s Office of Foreign Assets Control (OFAC) sanctioned Tornado Cash which is a well known "Mixer" that is used to "mix" cryptocurrencies such as Ethereum. That isn't that surprising of a news considering a North Korean hacking group has used it to launder hundreds of millions or even billions worth of Ethereum. The OFAC then listed a bunch of Ethereum address belonging to Tornado Cash that shouldn't be interacted with. That makes sense although it will be interesting to see how they enforce that.