Incorrect introduction point auth key location

Quoting from rend-spec-v3:

    "auth-key" NL certificate NL
     [Exactly once per introduction point]
     The certificate is a proposal 220 certificate wrapped in "-----BEGIN
     ED25519 CERT-----" cross-certifying the introduction point
     authentication key using the descriptor signing key. The introduction
     point authentication key is included in the mandatory signing-key
     extension.  The certificate type must be [09].

This is wrong because the introduction point authentication key is actually located in the CERTIFIED_KEY portion of the certificate and not in the extension.