I’m not saying this would happen, because it’d have a lot of side effects, but I could see a situation like how wrestlers try to drop as much water weight and everything else before weighing in, people drop as much testosterone before measurement. Again, this is purely a hypothetical and not a criticism of anything in our world today, just something I could imagine. Sex/gender is complicated, but hormone levels are also probably also not ideal measurements because it could lead to issues like the above, which I’m sure isn’t healthy. I really don’t know what the right solution is, but there’s clearly no perfect one.