Please help me to understand does enable Block Access of "Apps that don't use modern authentication" will break service account access because the service account does not use MFA?
@Kamal Pandey I understand you're in the device based restriction section in SharePoint admin. During authentication, legacy authentication clients don't support sending MFA, device compliance, or join state information to Azure AD. Consider using conditional access instead, there are now templates you can use for easy configuration Conditional Access - Azure Active Directory admin center.
You can read more about legacy authentication and unmanaged devices here
