Sorry to hear this @Maz1623
There are a few existing threads on the forum with tips in them with regards to such notifications issues which may help.
Just type in WhatsApp Notifications into the search bar on the forum.
Also do check your phone's notifications section and that of the app itself.
Some generic troubleshooting guides are >
Make sure the apps are updated in your Playstore and Galaxy Store.
Tryba soft reboot by turning the phone Off and On
Clear Cache Files from the phone's System Partition Section > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too.
If I can be of any further help then please don't hesitate. Take care. 😎
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "