Why can't the pop-up window on Whatsapp be disabled?

I have had the problem for some time that I get popup messages despite the fact that everything is displayed (in Whatsapp and in the settings) and this is synonymous only with a person Chat what surprised me. So slowly it annoys me because the news will always be opened without me doing anything. In addition, it also comes to the screen when it is angelatet it comes to call unwanted trouser pockets. I have already scoured the internet but found nothing. Have a Huawei Mate 20 fals that is necessary to know. Would be great if someone has a solution.

MfG and thanks in advance.

All chats at once I do not know but you can mute any chats -> no notification -> no POPUP