I would expect them to control for stuff like that, though.

What was the problem with that male vs female deep-learning test a few years ago?

That all the males were earlier in the day, so the sun angle in the background was a certain direction, while all the females were later in the day, so the sun was in a different angle? And so it turned out that the deep-learning AI was just trained on the window in the background?

100% accuracy almost certainly means this kind of effect happened. No one gets perfect, all good tests should be at least a "little bit" shoddy.