Note that they'll also have no avatar if they never set an avatar, and further if they deleted their account in the past, before the latest hoopla. So this way

Note that they'll also have no avatar if they never set an avatar, and further if they deleted their account in the past, before the latest hoopla. So this way of estimating the number of people who have deactivated lately necessarily provides only an upper bound on the total number of deactivations.