Some methods of money laundering that are difficult to track and disguise include the use of bitcoin mixers and NFT products. Centralized exchanges also do not apply KYC for small balances, it is possible for players to accumulate large amounts through small withdrawals from these exchanges.
Thank you for your comments. Yes, I totally agree that money can be laundered by use of mixers and NFTs as well. However, a ban on cryptocurrencies in itself won't stop any criminal from using crypto as a means of money laundering. Such criminals will continue to use crypto even if it is banned because implementing a ban is 1000x more difficult than introducing a ban.
Further, regarding KYC, as far as my experience goes, most reputed centralized exchanges do not allow any purchase of cryptocurrencies without the minimal KYC norms. Hence, these exchanges will have information on the user and of the transactions undertaken by the user. Once such data is available with them, they can track the aggregate of the transactions throughout a period and thereby identify large movement of crypto/cash. Government can then regulate the exchanges, requiring them to mandatorily share this information with them. Thereby, Government can track money laundering through crypto.
I hope this addresses the points you raised. Thank you again for your inputs. I would like to take up a separate post providing how Government can regulate the cryptocurrencies, also considering how few of the governments have already implemented these laws.