Hello EnterpriseArchitect,
Thank you for posting your query in the Microsoft Q&A Community.
I would advise you to perform this migration during off-peak hours as users may experience disruptions. You need to send a clear communication before going ahead with this. Another risk will be regarding the proper configuration. Misconfiguring the authentication methods could lead to lockouts or security vulnerabilities. It’s essential to configure the desired authentication methods accurately and thoroughly
To mitigate these risks, follow the steps below
- Document user settings, including phone numbers during the review process of your current MFA settings in the legacy portal
- Enable the new Authentication Methods in the AAD portal.
- Configure the desired authentication methods
Follow the link below for more information about this.
Let me know if further assistance is needed.
Babafemi