The QFN under-pad escape tests each via against pads grown with square corners, while check_drc grades the real pad shape, overstating clearance by up to 0.18 mm near a corner. On the fixture, 16 of 47 pads get dropped as no clear via offset, while with the grader's own check swapped in all 47 escape and both check_drc and kicad-cli find no violation.