OK, so suppose you and I were bad guys. You work on the code that interfaces with the TPM on a windows device, and I work at an insurance provider and write code that authenticates users.
Suppose we hatch a conspiracy to take our users out of the "consumer synced passkey system". And into one where you can use the authentication ritual as a channel where you can pass me unique bits re: this user such that we can later compare notes about their behavior.
What about passkeys prevents us from doing this? How do we get caught, and by whom?