When passkeys were first released, Bitwarden would not allow them to be deleted at all — the passkey deletion button was only made available some six months later, in response to user feedback. There was significant discussion about this on the forum in 2023–2024.
In the meantime, here is another feature request that you might want to support (it currently has no votes, so your support will certainly help the cause):
Your comments would fit better in that thread than here, so they may end up getting moved.