diff --git a/airflow-core/src/airflow/serialization/serialized_objects.py b/airflow-core/src/airflow/serialization/serialized_objects.py
index cadd701248e73..b2e3a7b591387 100644
--- a/airflow-core/src/airflow/serialization/serialized_objects.py
+++ b/airflow-core/src/airflow/serialization/serialized_objects.py
@@ -758,7 +758,7 @@ def serialize(
             return var.to_dict()
         elif isinstance(var, MappedOperator):
             return cls._encode(SerializedBaseOperator.serialize_mapped_operator(var), type_=DAT.OP)
-        elif isinstance(var, (BaseOperator, SerializedBaseOperator)):
+        elif isinstance(var, BaseOperator):
             var._needs_expansion = var.get_needs_expansion()
             return cls._encode(SerializedBaseOperator.serialize_operator(var), type_=DAT.OP)
         elif isinstance(var, cls._datetime_types):
@@ -1372,11 +1372,11 @@ def serialize_mapped_operator(cls, op: MappedOperator) -> dict[str, Any]:
         return serialized_op
 
     @classmethod
-    def serialize_operator(cls, op: BaseOperator | MappedOperator | SerializedBaseOperator) -> dict[str, Any]:
+    def serialize_operator(cls, op: BaseOperator | MappedOperator) -> dict[str, Any]:
         return cls._serialize_node(op)
 
     @classmethod
-    def _serialize_node(cls, op: BaseOperator | MappedOperator | SerializedBaseOperator) -> dict[str, Any]:
+    def _serialize_node(cls, op: BaseOperator | MappedOperator) -> dict[str, Any]:
         """Serialize operator into a JSON object."""
         serialize_op = cls.serialize_to_json(op, cls._decorated_fields)
 
diff --git a/airflow-core/tests/unit/serialization/test_serialized_objects.py b/airflow-core/tests/unit/serialization/test_serialized_objects.py
index cf56a42211fa3..86ab66f66bc09 100644
--- a/airflow-core/tests/unit/serialization/test_serialized_objects.py
+++ b/airflow-core/tests/unit/serialization/test_serialized_objects.py
@@ -563,18 +563,6 @@ def test_roundtrip_exceptions():
     assert deser.timeout == timedelta(seconds=30)
 
 
-@pytest.mark.db_test
-def test_serialized_dag_to_dict_and_from_dict_gives_same_result_in_tasks(dag_maker):
-    with dag_maker() as dag:
-        BashOperator(task_id="task1", bash_command="echo 1")
-
-    dag1 = SerializedDAG.to_dict(dag)
-    from_dict = SerializedDAG.from_dict(dag1)
-    dag2 = SerializedDAG.to_dict(from_dict)
-
-    assert dag2["dag"]["tasks"][0]["__var"].keys() == dag1["dag"]["tasks"][0]["__var"].keys()
-
-
 @pytest.mark.parametrize(
     "concurrency_parameter",
     [
@@ -643,7 +631,7 @@ def test_serialized_dag_get_run_data_interval(create_dag_run_kwargs, dag_maker,
     pre-AIP-39: the dag run itself has neither data_interval_start nor data_interval_end, and its logical_date
         is none. it should return data_interval as none
     """
-    with dag_maker(dag_id="test_dag", session=session, serialized=True) as dag:
+    with dag_maker(dag_id="test_dag", session=session, serialized=False) as dag:
         BaseOperator(task_id="test_task")
     session.commit()