Tested with PingCastle 3.5.0.37 and 3.4.1.35, both declare the kerberos.microsoftonline.com trust as type “Unknown: 5” wich could be named “Cloud Kerberos Trust” or “TRUST_TYPE_AAD”
The Trusttype 5 is described here:
And here is the note that it is documented in the protocols since 2023: [MS-WINERRATA]: Active Directory Technical Specification | Microsoft Learn
