We are also seeing various ad types on Mobile. You can use the Mobile emulator on the Chrome browser to check directly. Just click F12 and select a mobile device such as iPhone12 to view the page from a mobile perspective. With the Chrome extension you can view Mobile placeholders and make changes to them.
Alternatively, you can log in to your publisher dashboard to view and edit placeholders on Mobile. I just checked this page for you and perhaps this is what is causing the misunderstanding about the current placeholders. The placeholders that were added manually include top of page and sidebar only but there are also automatically generated placeholders.