Notifications not reflecting

Not receiving notifications for a few apps

I have an Iphone 14 promax with the latest iOS 17.4.1 installed.

Recently facing an issue where a few applications (eg: Whatsapp, instagram, gmail) do not showcase notifications to me - until I open the app, when the app refreshes and all the updates pull in at once.

I have tried multiple things:

1. Focus mode off
2. Low Battery mode off
3. Checked all settings of individual apps to see notifications are on
4. iphone notifications settings to see all are on
5. Background app refresh on
6. Privacy and restrictions off
7. Reset notification settings of individual apps
8. Have also tried offloading and reinstalling each app
9. Reset factory settings for full iphone
10. Restarted phone multiple times.
11. Shut off notifications for a few hours and then turning on again

and many other remedies suggested....

Still cannot figure why I can see notifications. This is very annoying and doesnt seem like an app problem (but an IoS problem). Can you please help!! Cannot find any rectification online