Note that there is a possibility this may not be intentional, but rather as a short term consequence of having to allow other browsers. The device prompting the user to specify which browser they want to use is evidence of this.<p>Likely, Apple will fix this later. I simply cannot see them intentionally pulling something like this while the EU is breathing down their necks, and if the change were intentional, it would have been a global change.
This is part of the compliance with "opening in your default browser" if the web site isn't specifically marked as a PWA then it just opens in the default browser. If it has a PWA manifest then it opens as a app using of course on Webkit as the rendering engine.