Static Orb’s specialization node “Storm Burst” makes it explode after 4 metres.
“Ball Lightning” removes the explosion, which sets the range to 4 metres thanks to “Storm Burst”.
“Recurring Orb” Sets the range to 2 metres when added on top.
Mike has confirmed that this is a bug and appears to be calculated from assumed speed and time, the orb basically moves 2 metres there and 2 metres back when it should be 4 metres each.