…Some users may also have UTXOs which are known to be high-risk due to where they originated from. The coordinator may decide not to include UTXOs which are likely to result in other users’ UTXOs inheriting that risk. Owning a high-risk UTXO will not prevent other UTXOs in your wallet from being coinjoined….
https://blog.trezor.io/coinjoin-privacy-for-bitcoin-11aaf291f23