Maintaining privacy with CoinJoin requires ongoing care: avoiding timing and amount correlations, address reuse, linking change outputs, consolidating mixed coins, and combining them with identity-linked funds. You also face intersection attacks, Sybil participants, malicious coordinators, wallet fingerprints, network metadata leaks, and identification through exchanges or merchants. The effective anonymity set may be much smaller than it appears, and additional rounds cost time and fees without guaranteeing proportional privacy gains. Bitcoin’s ledger remains public, so later spending can weaken earlier privacy.

You need to stay in CoinJoin forever.