Sure, it may just be any old nutkin, the camera zoom and Y'sh's reaction being merely for comedy. But think about this:

If there exists a tradition of employing shapeshifting magic in Tural, it would naturally coincide with Erenville's ability to identify us despite our changed frog appearance during our investigation into Labyrinthos at the beginning of Endwalker - remember, Erenville is from Tural originally. Yes, he's keen on discerning our behavior as distinct from regular frogs, but don't just brush it aside as his merely being sharp - the attention he pays to critters we wouldn't neccessarily even give second thought to might betray his familiarity with what might reasonably hide behind the facade of animals in the land he grew up in.

Of course such shapeshifting magic would not be mastered in a day's worth. Krile in the trailer clearly displays natural nutkin behavior - the peanut is a dead giveaway - yet at the same time she seems ruffled and frantic, perhaps excited, as though she had just been attuned to the shapeshifting form of a nutkin for the first time and was familiarizing with it - perhaps in an effort to balance not becoming overwhelmed by the animal spirit and fully transform into a nutkin forever and at the same time maintaining the nutkin form and not immediately shifting back into lalafell mode. I assume that Krile is on a trial here to find something in the city while in nutkin form, a quest given by her master, who is introducing her to the shapeshifting arts.