Safari 26 turns many websites into app-like experiences on your iPhone and...

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

Safari 26 turns many websites into app-like experiences on your iPhone and iPad. When you add a site to your Home Screen, it behaves more like a standalone app with minimal browser elements