Wasabi Coordinator. You have to choose a Coordinator that will most likely not Scam you, according pretty much to your own subjective calculations which can never be perfect.
It's pretty simple. WabiSabi is trust-requiring, because you need to trust that the coordinator will not turn evil and attack their own users. It's literally written in their whitepaper:
An attacker attempting to Sybil attack all CoinJoins would need to control some multiple of the combined Bitcoin volume contributed by honest participants, and to successfully partition honest participants to a sufficient degree. [...] However, this does not protect against a malicious coordinator which is only bound by liquidity and mining fees.
Following the next paragraph, we can see there are other attacks it can execute as well:
A malicious coordinator may tag users by providing them with different issuer parameters. When registering inputs a proof of ownership must be provided. If signatures are used, by covering the issuer parameters and a unique round identifier these proofs allow other participants to verify that everyone was given the same parameters.
A malicious coordinator could also delay the processing of requests in order to learn more through timing and ordering leaks. In the worst case, the coordinator can attempt to linearize all requests by delaying individual to recover the full set of labelled edges. This is possible when k = 1 and users have minimal dependencies between their requests and tolerate arbitrary timeouts but issue requests in a timely manner
Similarly the coordinator may delay information such as the set of ownership proofs or the final unsigned transaction. In the case of the latter, this can be used to learn about links between inputs. This is because a signature can only be made after the details of the transaction are known. If the unsigned was only known to one user but multiple inputs have provided signatures, it follows that those inputs are owned by the same user.
Then, it probably wanted to say "the coordinator must
be trusted":
Since the coordinator must trusted with regards to denial of service a more practical variant of this attack would involve more subtle delays followed by sabotaging multiple successive rounds during the signing phase in order to learn of correlations between registrations while maintaining deniability.
It can attack with Sybil attack. It can attack otherwise too. Perhaps Kruw interprets "trustless" differently than the rest of us. This wouldn't surprise me, considering I've been questioned about my choice of words when speaking with him before.
