Something strange. A link that is known to be valid, when clicked, doesn't take the user to the report itself. Rather, it takes users to the Power BI login page. This behavior takes place from Microsoft Word and Excel. However, the same link from Microsoft Teams or Outlook, when clicked, takes you directly to the report itself bypassing the login page. This is the desired behavior. Both sets of responses are observed repeatibly.
I think this represents a bug. A link, whether it's valid or not, should take you to the same place whether it's clicked from Word, Excel, Teams, Outlook, or really any other program. I'd like to submit the behavior for bug research, please.