Change default all_carts_are_expired value to null

authentication/serializers.py

@@ -26,7 +26,7 @@ class UserAuthSerializer(serializers.ModelSerializer):
 
         result['transaction_status'] = None
         result['cart_id'] = None
-        result['all_carts_are_expired'] = False
+        result['all_carts_are_expired'] = None
 
         if instance.cart.exists():
             result['transaction_status'] = instance.cart.last().transaction_status