With HDMI source and keystone correction image ratio is not what it should be, image is taller than it should. Circles are ellipses, people thinner than they should etc.
Since screen adjustments do not work with external sources, this can not be corrected if the source has no over- / underscan correction.
I wish I had noticed this while I still could have refunded the item, but it’s long gone now. Probably unrepairable with software updates.