The rotation introduced using the QT_QPA_EGLFS_ROTATION environment variable should not be present on the screenshots taken with QScreen::grabWindow() currently the screenshots taken are rotated along the requested rotation and cut in size so the width matches the height. For instance when using QT_QPA_EGLFS_ROTATION=90 the expected screenshot of the lineedits example would be:

But what gets captured is:

This is an issue for Squish which takes a lot of screenshots while testing applications.