Isn't that the light element on the traveler in the teaser?
As you can see it's clearly not cryo traveler, the cryo traveler has a bluish color, while the one in the beginning of the teaser is clearly white.
Could it be that just like in 5.3 where we got Pyro? We get cryo as usual like all the other elements and then we get the light element in 7.3? Because in Natlan act 4, one of the questions you can ask the Lord of night is about the element energy and the abyss, "light reflects into seven colors, that we call a rainbow, that's the concept of element energy", so if we take into consideration that Nathan was supposed to be before Snezhnaya, it would make sense to mention that before we get to it.
(Edit) it turned out to be a lighting mistake (again) anyways sorry for making such a big thing of nothing important...