qml TextInput scrolls the screen down for no reason.

Since Qt 5.9, the TextInput qml element has a strange behavior on my iPhone 7 (retina display). When I press a input the screen with scroll down for no clear reason. I understand that it could sometime scroll up to allow to see the input while the keyboard is visible, but here it does the opposite. I suspect the keyboard/input overlap computation not considering the screen density.

I attach a sample source code and two screenshots to show what I mean.

I could reproduce with all Qt releases from 5.9 to 5.10. 5.8 works fine.