QImage::save writes corrupt JPG files on iOS

The JPG imageFormat plugin writes corrupt images on iOS. It works fine on other platforms, also worked fine with Qt 5.9.5.

Simplest way to reproduce:

QImage(320, 240, QImage::Format_RGB888).save("test.jpg", "JPG");

The bug is likely related to the embedded libjpeg(-turbo) library. The output is still corrupt when I'm using libjpeg functions directly (linking directly to Qt's libjpeg).