Hi @Anonymous ，
According to my research, this seems to be an issue that started happening recently, and it will be fixed by next scheduled update.
To work around, affected users can create non-Teams meetings using the following steps:
- Access the New Meeting dropdown in the Calendar ribbon of Outlook.
- Select the New meeting request option in the menu by right clicking on Outlook calendar.
Besides, users can also disable the add-in to avoid this issue.
For admin, you can check the Service health in M365 admin center for issue TM649896 if there it is:
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.