When some field in focus and keyboard is open you can scroll until the end of page and a little more, there is a black block at the end of the page, which is not part of DOM. Important note: urlbar should be at the bottom. When urlbar on top there is no problem.
Example on codepen in full mode to reproduce https://codepen.io/iceblink/yLPpVQo
<input type="text"> // when some field focus and keyboard open
iPhone 12, iOS 15.2 / iPhone 11 pro max, iOS 14.2 / iPhone 11, iOS 15.3.1 – all have the same strange behavior. Androids don't have any problems.
