Your Wasabi analyzes the anonscore of every transaction after it happens.
Wasabi was the Bitcoin wallet that calculates some anonymity level, and it's still by far the most sophisticated.
What Seth is concerned about, is that you cannot PREDICT what outputs and anonscore a future coinjoin will bring you. That's great, because the attacker can't predict it either.
No need to trust my words, here is the code, read it.
