Yes I think this is iOS issue, when push api was experimental you could at least get it working after enabling in settings and adding to homescreen - push messages were received instantly as expected. Now they're only delivered when you manually open the pwa. I've spent some time looking for an issue on our end and I don't see any. I'm not sure this was a deliberate choice - why graduate this from experimental and then break it? Seems more like a bug, but who knows.