Notifications on my iPhone and laptop are not working

For the past two months i have been struggling to get notifications for many app's:

• Whatsapp
• Viber
• Microsoft Teams
• Slack
• Telegram
• and probably more

I have done checks if my notifications are on... they are on!

I have looked if "do not disturb" is on... it's not!

I have done everything what any forum asked me to do and there is nothing that changes it.

I have shared this problem with my colleagues and some of them have the same problem, but there seems to be no cure.

Example for whatsapp (my primary messaging app):

• I only see the messages I received when I open the app, no signs of any activity is shown before that
• I never get a notification that I am receiving a call on whatsapp, resulting in missing all my incoming calls
• On rare occasions my phone notifies me there are messages, but there is no pattern.

It seems to be a general problem from Apple, but I don't read about it anywhere.

It would be great if the answer would not be "check your notification settings" or "see if your do not disturb is on" because I have done that and that is not the problem.