I literally provided a citation.
> Syncable? Yes. Exportable? Yes. Clear text? Sure, behind the scenes. Exportable as clear text? Yes, but not intended.
A syncable credential is by necessity representable in clear text at some point. In comparison, resident WebAuthn private keys NEVER leave the secure device.
> [1] https://www.w3.org/TR/webauthn/
WebAuthn is a _superset_ of Passkeys. Here's the citation from your own linked page:
> This use case illustrates how a consumer-centric Relying Party can leverage the authenticator built-in to a user’s devices to provide phishing-resistant sign in using multi-device credentials (commonly referred to as synced passkeys). ... > A backup eligible public key credential source is referred to as a multi-device credential whereas one that is not backup eligible is referred to as a single-device credential. See also § 6.1.3 Credential Backup State.