I solve it.
The reason is that the system administrator gave me wrong AAD role. My AAD role should be AAD Global Administrator but the administrator gave me AAD Global Viewer.
And my functions using private links to prevent outbound access. And I created a managed private endpoint in ADF, but cause I am only a viewer, this endpoint doesn't obtain permissions to access fqDNS setting in another private endpoint.
And that fqDNS is https://******.azurewebsites.net
To solve it, you need to remove maneged private endpoint, obtain correct role and create it again.