Why do you think CoinJoin users are no longer allowed to choose which UTXOs to mix? Users may never notice that some of their UTXOs were analyzed or blacklisted because everything happens behind the curtain. For this reason, we aren't going to see reports about explicit censorship cases: unwanted UTXOs get blacklisted silently, and we shouldn't expect full transparency from people (Wasabi Wallet devs) who think users are too stupid to manage their own privacy. Given all this, it probably makes sense to test the software (or rather a zkSNACKS server behavior) in another way, namely by feeding it with outputs that any blockchain surveillance firm will deem dirty and then looking if some of these outputs are never getting accepted into a CoinJoin round.