Safari 26 brings a new way to experience websites on iPhone and iPad by making...

https://wiki-club.win/index.php/What_Happens_When_Screen_Orientation_Changes_in_a_Safari_Web_App%3F

Safari 26 brings a new way to experience websites on iPhone and iPad by making them feel just like apps. When you add a site to your Home Screen, it opens in a clean, full-screen view with no browser bars—kind of like a native app