Workaround available
https://www.bleepingcomputer.com/news/microsoft/microsoft-outlook-is-disabling-teams-meeting-add-in-how-to-fix/
Microsoft is investigating a known issue affecting Outlook for Microsoft 365 users and preventing them from creating Teams meetings using the app's ribbon menu.
The Teams Meeting add-in, as its name says, can be found in the Calendar view and it enables Outlook users to schedule a Teams meeting from Outlook.
Workaround available
Sep 19, 2022, 5:14pm UTC
https://www.bleepingcomputer.com/news/microsoft/microsoft-outlook-is-disabling-teams-meeting-add-in-how-to-fix/
> Microsoft is investigating a known issue affecting Outlook for Microsoft 365 users and preventing them from creating Teams meetings using the app's ribbon menu.
> The Teams Meeting add-in, as its name says, can be found in the Calendar view and it enables Outlook users to schedule a Teams meeting from Outlook.