Skype flooding Azure sign-in logs with legacy connections.

Hi

I am testing Azure AD Conditional Access policy to block legacy connections (https://docs.microsoft.com/en-us/azure/active-directory/conditional-access/block-legacy-authentication).

I run into an issue with Skype constantly generating legacy authentication attempts, most likely EWS calls.

This seems to be happening randomly for a significant portion of my test group.

Office version does not seems to be a factor (versions vary between 1808 and 1903).

I talked to some of the affected users and nobody noticed any disruption in normal Skype operations.

I need to know what it is and how to get rid of it.

Otherwise it will be very hard to track any real affected users once the my test population keeps expanding.