I’d have thought the stars should be on the right side when hanging vertically, since it would be rotated 90 degrees clockwise from the standard position.
I have no idea which way is correct, this is just my intuitive reasoning.
When displayed either horizontally or vertically against a wall, the union should be uppermost and to the flag’s own right, that is, to the observer’s left.
TBF, it does have different instructions about how to display the flag outdoors, hard to tell from this perspective if it was actually hung properly.