We have a development and production Customer Self-Service portal with the setting Authentication/Registration/AzureADLoginEnabled = true. This adds the Azure AD button under Sign in with external account section...which I assume is the reason we were alerted to these apps being affected by the deprecation decision by Microsoft to no longer support the Azure AD Graph API after June 30, 2022.
None of the documentation I was referred to describes what exactly needs to be done by us to migrate these portals to use the Microsoft Graph API instead.