With Safari 26 on iPhone and iPad, many websites now act more like standalone...

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

With Safari 26 on iPhone and iPad, many websites now act more like standalone apps. When you add a site to your Home Screen, it opens without the usual browser bars, giving you a cleaner, more app-like feel