I just tested with my iPhone and I cannot reproduce your issue. Have you made sure that the PowerApps app is the latest version from app store? If not, please try to update and try again. Also, please try the same app on different iPhones to have a test.
Community Support Team _ Mona Li If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
I just started experiencing this today. I can fix it using the browser's dev console (in SharePoint) if I locate `#SharePointForm1container > .appmagic-borderfill-container` and change the `overflow` property to `auto` (currently set to `hidden` in: https://pa-static.azureedge.net/resource/app/tahoqc00pflk3/css/canvas.css), but obviously this doesn't do our other users any good.