How will they determine whether the transaction is related to "crypto"? In particular, if it is P2P. Transactions "from" and "to" people who rarely change crypto can't be identified as involved in "crypto", because it look like ordinary transactions between bank clients.

When carrying out P2P trades, if the sender of the fiat unknowingly adds the word "crypto" or anything crypto related as shown above, the financial institutions have put in place surveillance system that can detect such transactions.
Then how do you implement? Exchange for cash in person? Do you think this is safer?
We're still performing transactions via P2P on CEXs but with experienced traders who would not be dumb enough to make such silly mistake.