Update (4/12/23): This feature was enabled in our worldwide and 21Vianet clouds in November 2022. All tenants in these clouds will see the changes. Rollout to our GCCH and DoD clouds has been paused ...
Updated Apr 12, 2023
Version 11.0
Blog Post
What we have recently discovered that Office profile cards are affected as well. We have been using custom attribute (cn from on-prem AD) as described https://support.microsoft.com/en-us/office/customize-the-profile-card-in-win32-apps-using-registry-keys-449afd21-6e5e-4b1f-8051-6515630d7537. And while we had mailboxes in Exchange on-prem, everything was fine and it was showing value from local AD cn attribute. However, once we migrated our mailboxes to Exchange Online, users started seeing GUID instead of expected value on some profile cards. So we realized, that this "name" change is affecting the profile card as well, event though we could not find it documented anywhere. Nevertheless, we are considering switching to one of "ExtensionAttributeXX" attributes as a solution, it just will require some changes in our on-prem automation.