in theory. in practice, most coinjoins are very obvious on-chain,
and some exchange customers are paying the price for it. taproot, cross-input aggregation, and less obvious coinjoin mechanisms will mitigate this in the future, but for now all i can say is,
be careful of your proximity to exchanges and AML/KYC enforcing services when engaging in coinjoins.When an exchange harms your privacy applying weird heuristic to your transaction before or (worst) after using them, just stop using it.