On Thursday, December 8, 2022, several security improvements will be applied to Microsoft online services (including Teams, OneDrive, and Sharepoint):

• Downloads of potentially malicious files will be prevented by SharePoint online.
• User reporting of fraudulent multi-factor authentication requests will be enabled. 
• Guest accounts will be denied access to enumerate users and groups in Azure. 
• Microsoft 365 email users may see a notification when receiving an email from a sender for the first time. 

No significant user impact is expected.