The Experience outcome card in Site page view experiences is associated with Edge experiences, a type of Composer experience that executes on the CDN edge before content is loaded to the browser.
Within Edge experiences there is a Set experience outcome card that lets you set the outcome of the edge-side decision to determine whether content should be loaded in full or in a restricted form. Find out more about the behavior here.
Another layer of this safety net is an app-wide Fallback offer described here.