WhatsApp testing a redesign for its calling screen so you’ll know where to tap to hang up،
WhatsApp generally has all the essential features of a proper messaging app: group chats, broadcasts, communities, voice, video. However, as versatile and popular as the app is, WhatsApp's user interface can sometimes seem very clunky and outdated. Luckily, it looks like Meta is listening and doing something.
The new WhatsApp call screen UI | Source: WaBetaInfo
This is important because the old back button created a lot of confusion. Because it was ambiguous, many users thought that by clicking this back button they were ending the call completely. Obviously that wasn't the case, but with this new minimize option you get a clearer indication that tapping it just hides the call screen, without hanging up.
Additionally, the buttons are designed very distinctly to visually separate them from the rest of the screen. Judging from the screenshot above, I don't think the new buttons leave room for misinterpretation. This is a small but thoughtful design change that can make a big difference.
WhatsApp clearly wants to make the calling experience as painless as possible. It's not the most revolutionary update, but it shows that they're listening to how people actually use the app and tweaking things accordingly. Sometimes the best features are the ones you miss.