Outside the sphere of crypto, this is called "washing" or "laundering" ("cleaned", etc. Anything along this line). "Laundering" is the legal term). Such acts are typically traceable, but generally fly under the radar. Once someone is aware that the money is being washed it is usually uncovered (AFAIK).
Washing crypto would seem even more difficult because transactions are all accounted for. So I'd assume a cleaner would need to have random time variance in redistribution so collisions aren't found. But also, money has to be spent or converted, so that's a big way you could uncover it. Money is harder because cash is still a thing.
1) See that money is transferred from account to washer (instant flag)
2) Search for accounts associated with initial fraud and watch for extraction.
I work in crypto. Transactions can very much be traced. There's no trace of Quadrigas cold wallet holding any large sums of BTC. It's still a mystery what, exactly, did they do with customer funds. It'll be uncovered eventually once enough time has been given to forensic examiners to go through the transactions of the exchange.
Washing crypto would seem even more difficult because transactions are all accounted for. So I'd assume a cleaner would need to have random time variance in redistribution so collisions aren't found. But also, money has to be spent or converted, so that's a big way you could uncover it. Money is harder because cash is still a thing.
1) See that money is transferred from account to washer (instant flag)
2) Search for accounts associated with initial fraud and watch for extraction.