No, the default isn’t on. It just seems to choose answers that you had put in previously.
I hadn’t filled out anything on the form but you can see it just opened with options already chosen. The only default I have turned on is the date/time.
Yes, when testing forms it can be uncofortable the way Airtable saves your last inputed values.
This means that when you open the form again: it loads with the values you set in your last un-submitted form, which I also mistook before as a prefilled value.
New users opening the form will see it blank.
To be sure click the “Clear form” button and then open the form again: it should now load empty.