Microsoft is making it easier for owners of Teams shared channels to request help if they run into a trust problem when adding a member from another domain. If Teams detects a problem with a missing trust, it flags the error to the channel owner and offers a link to a web page to seek additional support. Of course, the tenant might decline to trust the domain the channel owner wants to use, but that’s a different story.
https://office365itpros.com/2023/07/18/shared-channels-requests/
