Thanks for your feedback @PaulWebster and sorry for the troubles.
I’m guessing your device is a first-generation iPad Air and it cannot be updated to iOS 13 or later?
It’s a bit tricky to add a back button to the HTML-only version because we don’t have the same Javascript framework there as the main app and we can’t easily detect that the user is in the DiscourseHub app.
One helpful tip is that the mobile app has a gesture for dismissing an open site. You can swipe downwards to dismiss, starting the swipe roughly at the location of the site logo.
This is sadly not possible. Some features in the Javascript bundle of the app now will completely break in old browsers. It’s not just a matter of some features not working properly, the whole app will return a blank page.