It doesn't really work. It's just fiddly and often doesn't do what I want it to. I don't even understand how it's supposed to work. I tap at the top so the address bar shows up. I tap the address bar. It thinks I want to enter a URL, so it changes the view.

You're supposed to tap at the very top, near the time or the notch depending on what device you have. This works in all apps that use standard scroll views.

Double tap not on the address bar but above, on the time in the OS top bar.

Works on ios chrome too, but for both it breaks down when a call/gps banner is up there

Even more: it is a global feature that is supposed to work for any view controller with a scrollable view. (I wouldn't describe it as "double tap", though: you tap the status bar once, but in Safari the status bar is hidden as you scroll down so you have to tap the top of the screen to reveal it.)