When you receive a push notification on the iOS PWA it will correctly open the correct PWA for you.
However, if it’s open already, it won’t route you to the correct target URL of the notification, like for example the post URL on a notification for a reply.
They key piece there is probably this comment from Brady Eidson (Webkit engineer):
In my test case it’s working because I’m postMessaging to a new client opened via clients.openWindow
If I attempted to matchAll and reuse an existing window client, I would fall into this same trap.