Whatapp problem

Hi brothers

Bro i have iphone11 pro max and 2 i ago i buy in saudi arabia brand new and than i come back to pakistan so in future i can not go outside from country first i go so buy this iphone somedays i have face problem in whtappp(so the probelm is that when i on dark mode or white mode in phone and that i open whtapp and i also change the chat wallpaper which is own in whtapp so when i open someone chat and i back it to close chat is the screen is blinking with straight line i share pic you see it bro now it look a straight line but when open and and close with right to left and the screen is blinking i have latest software so what the pro come in it plzzz reply