Note how DAG policy works with default_args (#24804)

Co-authored-by: Tzu-ping Chung <uranusjr@gmail.com>
(cherry picked from commit 298be50)

docs/apache-airflow/concepts/cluster-policies.rst

@@ -54,6 +54,10 @@ This policy checks if each DAG has at least one tag defined:
 
     To avoid import cycles, if you use ``DAG`` in type annotations in your cluster policy, be sure to import from ``airflow.models`` and not from ``airflow``.
 
+.. note::
+
+    DAG policies are applied after the DAG has been completely loaded, so overriding the ``default_args`` parameter has no effect. If you want to override the default operator settings, use task policies instead.
+
 Task policies
 -------------