Azure AD v2
Usage To allow your WordPress website users to Sign in with Microsoft, you’ll need to register your website with Microsoft first. To do so, you must create an App Registration in (your tenant’s) Azure Active Directory. Until May 2019, Microsoft offered two versions of the Azure AD endpoints: v1.0 and Preview which then became v2. For App registrations created after May 2019 it's safe to assume that your App registration is compatible with the V2 endpoint and this option should be checked, which it is by default for new plugin installations.
Important If you created your App registration before May 2019, it is strongly recommended that you upgrade your App registration.
Related See the online upgrade guide (see https://docs.wpo365.com/article/4-upgrade-to-azure-ad-app-registration-v2-0).
Default value Checked.