Push notifications not working after transferring data from one iPhone to another

I transferred data from iPhone XR to iPhone 12 using the Quick start wizard / Device to device migration. I wasn't getting push notifications for one app that I was already installed on my old iPhone.

I checked the push notification settings for that app, and everything was enabled as before.

• I toggled the settings to off/on. That did not help.
• I tried to log out and log back in to that app, but that also did not fix the issue.
• Then I deleted and reinstalled the app, and then at the time of login, the app asked me whether I want to allow push notifications. I clicked Allow, and now notifications for that app have started working.

For another app, I noticed that I was getting push notifications, but I could not see the long press "Action" that I was supposed to see. (e.g. PagerDuty alert push notification has an action "Acknowledge incident", Or Gmail has "Reply" and "Bin" actions)

Again I had to delete the app and reinstall it, and then the action appeared on the push notification long press.

The catch is, since I'm not getting the push notifications, I cannot find out how many other apps are broken this way.

This is probably a bug with iOS where it silently resets push notification permissions after the transfer, and does not notify the apps that it did that.

I think the only way out from this is to somehow reset push notification permissions for all apps (is this even possible?), and set them again one by one as I use the apps.