also apply preprocess to diagaonalizing gates

pennylane/resource/specs.py

@@ -194,8 +194,14 @@ def specs_qnode(*args, **kwargs) -> Union[list[dict], dict]:
         batch, _ = qml.workflow.construct_batch(qnode, level=level)(*args, **kwargs)
 
         for tape in batch:
+
+            program = qml.workflow.get_transform_program(qnode, level=level)
+            (diag_tape,), _ = program((qml.tape.QuantumTape(tape.diagonalizing_gates, [])))
+
             info = tape.specs.copy()
 
+            info["num_diagonalizing_gates"] = len(diag_tape.operations)
+
             info["num_device_wires"] = len(qnode.device.wires or tape.wires)
             info["num_tape_wires"] = tape.num_wires
             info["device_name"] = qnode.device.name