The additional_data object is not sent when placing an order

I follow the instructions of the example and the payload object is loaded with information, after the order is complete, this information that I send does not appear anywhere in the magento, not even in the database

Additional data is mostly for custom payment methods. It will be used during order’s processing but it won’t be accessible in dashboard.

But if I send the information from the api, it should be saved somewhere in the database, right?