DC barrel jack datasheet dimensions!
It looks correct to me. But I can see the reason for the confusion. The PCB layout diagram should have been rotated 180 degrees so it would be more obvious.

The 1mm width of the flat pins would fit with plenty of clearance against the 1.6 mm length of the rectangular hole. The thickness of the pin (not specified) will clear the 1mm hole width.

A 1.6mm round hole should meet the spirit of the spec. Would just need more solder than a rectangular hole.