This was all working for me for 2 shared mailboxes yesterday (although using the entra ID accounts associated with them, but now today when I try to add a 3rd using the exact same method, it won't work and I get the error above:
array ( 'code' => 'Gone', 'message' => 'This API version has been deprecated.', )
What's worse, is when I tested one of the other shared mailboxes by deleting the token, that one is also no longer working - settings unchanged.
I've tried unticking the strict matching and using an account (with it's own mailbox and license) that has full delegation (send and full access) but I'm still getting the error
I've even tried using an account with Global Administrator, that can access the mailbox via owa, has full send+manage permissions, has Application Administrator on the app, and still same error
(Application also has admin consent granted - clicked on several times today just to make sure)
OSTicket: v1.18.1 (0375576)
Oauth2 plugin: 0.6