If the filter is mounted upside down then there is no need for a anti-drain valve…the oil will never leak out.
That was one of those funny tests people would use to discredit Fram filters. They’d cut open two different filters (Fram and one other brand) and show that the Fram didn’t have a anti-drain valve, but the other filter did. The filters were for different vehicles. The Fram fit on an engine where it was mounted upside down (threads facing up). The other was for a engine where the filter right-side up (threads facing down). The Fram filter for that application also had an anti-drain valve.