No/ delayed notifications

After updating my iphone XS max to IOS 15 i stopped receiving notifications for the social media apps, i tried the following steps but it didn’t help:

1- made sure that all notifications are turned on

2- made sure that DND is turned off

3- made sure that low battery is turned off

4- made sure that background refresh is turned on

5- made sure that low data usage is turned off

6- turned the Bluetooth off

7- restarted my iphone

8- reset all settings

can anyone suggest a solution for me ?