Let’s start with the basics.
The auto-focus mechanism of the camera focused the lens – mostly! – on the window frame. If these are distant objects outside of the plane, they are out of focus.
If these are reflections of interior lights, there are two factors which could cause them to be out of focus.
-They are more distant than the window frame. An image in a mirror or window is in focus when you take into account the total distance of the camera from the mirror or window PLUS the distance of the object from the window.
-The image of the window frame itself is not in good focus. If the lens is in focus part of the way between the window frame and infinity ... Read even more
