After arriving on the mainland from the Icy Area, Snow became accustomed to constantly hiding her true form with her illusions, after many pokemon on the southern end of the continent reacted negatively to her being a Zorua. She continued this upon arriving to Treasure Town, even having planned on joining the guild in a disguise. But when she found Celeste collapsed on the beach, Snow was so overcome with panic at seeing an unconscious pokemon that she'd forgotten to put up a disguise until it was too late
However, she was surprised to find that Celeste had no reaction to Snow's true appearance, and simply treated Snow like any other pokemon. Snow quickly figured that Celeste actually had no idea what a Zorua was, but seeing how trusting Celeste was of her despite her appearance gave Snow the courage to try and join the guild as her true self. As it turns out, most of the pokemon both within the guild and in Treasure Town can't even tell what kind of pokemon she is, considering she's a rare variant of an already rare pokemon
Snow uses this to her advantage, exclusively going by her name so that she's never asked for her species name, and vowing to herself to never use her illusions again, so that the town, the guild, and especially Celeste, never learn of what she really is
