https://techcrunch.com/2022/08/08/treasury-tornado-cash-laundering-stolen-crypto/

The U.S. has sanctioned decentralized cryptocurrency mixing service Tornado Cash for its role in enabling billions of dollars worth of cryptocurrency to be laundered through its platform.

Tornado Cash, along with other mixers such as AlphaBay, enables customers to conceal the source of their crypto funds when participating in a transaction in exchange for a fee. It blends potentially identifiable or tainted cryptocurrency funds with others to obfuscate the source and destination of crypto assets