On this article below, below is mentioned
https://docs.microsoft.com/en-us/azure/active-directory-b2c/active-directory-b2c-faqs
\" Consider using
Currently, you must use Azure AD Graph API to manage users in an Azure AD B2C tenant, since Microsoft Graph doesn't support a few of the user properties (including the creationType property) that are used by Azure AD B2C.
This Microsoft Graph or the Azure AD Graph article indicates that the current gap between the Microsoft Graph and Azure AD Graph APIs for managing users in an Azure AD B2C tenant.