Hi @seenfai,
Welcome to the Auth0 Community !
The reason as of why you are encountering this behavior is because Auth0 does not block the Enterprise MFA, so developers can try it out. However, if the feature is regularly used for over three months, the tenant admins will be asked to upgrade the subscription.
You can check out the Entitlements for Enterprise MFA Feature.
Hope this helps your case and others as well!
Thanks,
Remus