Sorry, there’s no way you could tell that one finger touches the screen sooner than the others in that video. Even if it was true.
Regardless, even when I intentionally roll my 3 fingers so that there’s no question that they’re touching one after the other, redo still works as it should 8 times out of 10. Obviously the developers accounted for the fact that we’re not robots and can’t touch the screen perfectly with all three fingers at the same time.
The bug is that it doesn’t work every time.