Safari 26 brings a smoother, app-like feel to many websites on iPhone and iPad....

https://bizzmarkblog.com/why-does-my-ipad-web-app-feel-different-from-the-same-site-in-safari-tabs/

Safari 26 brings a smoother, app-like feel to many websites on iPhone and iPad. When you add a site to your Home Screen, it now opens without the browser’s usual bars and controls—just like a real app