I know decided to file a bug for Qt on this as we had a report for Neptune for a while.
Neptune's code uses OpacityMask to render pictures with people framed in a circle in the Phone application. It works well on all platforms on 5.14.1, excepting the desktop Linux where the Phone app runs in multi-process, but the unlaying Qt is build without "-opengl es2" . On the recent builds the phone app does not show pictures with people at all. Removing OpacityMask makes pictures with people show up in square frames.
See the linked issues for details and esp the
AUTOSUITE-1405 which contains some research.