Question Does arkit use any code from apple to help with face tracking?

In Snow (the ios app), it tracks your face all the way to the edge of the screen. Even if less than half your face is visible, it's already tracking it remarkably well.

But I ran the latest AR kit demo scenes, for the facial tracking, which I downloaded from github, and like basically your entire face has to be in the picture before it finally detects it.

So clearly Snow has much better facial tracking, are they using their own facial tracking algorythms? Or if they and ARKit are both using the same apple SDK for facial tracking (assuming that's how all this is working), then is there some setting I can enable to get it to track faces at the edge of the camera?