@karthi & @suryakant84, do you have any further findings on this topic? We are experiencing the same on our app too. In fact, we glad iOS 13 could actually wake the app upon receiving silent notification for performing minor updates. We are however doing extra work to handle cases depending on the user OS (iOS12/iOS13) which is not great for the project.

Possible to get 2 cents from any Apple Team Member, or community members?

The rest, please correct me if I'm wrong. But as far as Im aware, you don't get Push Notification to deliver on Android and iOS on the same time. Example, my app is relying on Firebase to push out the Push Notification once sent out via Portal. I have always receive notification first on iOS, following about 20 - 40 seconds later on Android. It all depends on the service provider you are using. Like my case Firebase, I have no control over the time.