Methods to Get User Identity and Claims in a .NET Azure Functions App include:
ClaimsPrincipal from the Request Context
The ClaimsPrincipal object is also available as part of the request context and can be extracted from the HttpRequest.HttpContext.
User Claims from the Request Headers.
App Service passes user claims to the app by using special request headers.
Reference:
https://levelup.gitconnected.com/four-alternative-methods-to-get-user-identity-and-claims-in-a-net- azurefunctions-app-df98c40424bb