I am also facing problems with WhatsApp on Note 20 Ultra. The call goes on mute when the screen turn off to save battery. I need to click on the screen all the time to keep the call on going which is not good.
I've been whatsapp for about 10 years. Been great. Now Facebook is truncating pics and videos to a very low quality. Such a shame. Now since I got my note 20, it will also not send any videos close to or over 1 min long without doing something very strange. The video after so about 20 seconds will speed up very fast than freeze after about 10 more seconds but the sound from the video is playing normal. I've un-installed and re-installed several times with and without old database. Very frustrating and whatsapp just sends me automated replies. Maybe Samsung can address the issue. Is anyone else experiencing this? I haven't made any calls using the app to see if the issue is going on.