What u mean by screen transition ?
Back ground app refresh should be tt app will once a whie check and refresh to see if there's any new messages.. More timely for user to get messages, but guess may compromise a bit of battery life
On the other hand, what about users that still haven't update their WhatsApp app version to the latest one (that has Background App Refresh capabilities built in)? I think they are still being notified of incoming WhatsApp messages even though their WhatsApp is running in the background without that Background App Refresh feature right?
I think someone posted in a prior post that having Background App Refresh enabled for the latest version of WhatsApp simply means when the user launches WhatsApp, there wouldn't be a delay, i.e. the "Connecting..." status when the user gets notified of an incoming WhatsApp mesaage & him launching the app itself to see the message. However, I'd Background App Refresh activated, for for my case, the "Connecting" delay still occurs when I launch WhatsApp to view a message that I was notified of.