add warning

backend/open_webui/utils/oauth.py

@@ -282,6 +282,7 @@ class OAuthManager:
 
                 name = user_data.get(username_claim)
                 if not name:
+                    log.warning("Username claim is missing, using email as name")
                     name = email
 
                 role = self.get_user_role(None, user_data)