In a flashback scene in the movie Thor, we see Odin transforming Loki's appearance from that of a Frost Giant to that of an Asgardian (more here Why does Loki look like he does in the movies?). Moreover, in the same movie it is shown that Odin's spell is not immutable: Loki's appearance change back to his natural blue skin when a Frost Giant touched him and when Loki uses the Casket of Ancient Winters.
In Loki episode 1, when Loki tries to use his powers in the TVA, Ravonna tells him
Magic powers? They are no good in the TVA.
implying that magic cannot be used in there. Moreover, later in the episode it is shown that even the Infinity Stones don't work in the TVA and, recalling that the Stones bend reality, time and space, they seem in a certain way "stronger" than Odin's enchantment.
So when Loki enters the TVA shouldn't his appearance revert back to that of a Frost Giant?