It's possible (likely imho) that there is some missing factor that we have yet to discover that explains the funky nature of the data. Something about the people rather than a property of the disease. Almost like an allergy: peanuts are quite fine for everyone to eat, except those with severe peanut allergies.

What we do know is that it can't be quite "there were zillions of people infected so when we talk about 1% IFR really it's 0.01% so everything is fine", because there are accumulating bodies in various localized places around the world. There's nothing we know to say that pattern wouldn't repeated everywhere.