PkHeX showing weird sprite for Hippopotas

[Sacred Fire]

Title. Not like a game breaking bug or anything but I have two Hippopotas (the left one is male, the other is female) and there's some weird thing layered on the sprite of the female one. Anyone knows what it is?

Edited April 9, 2020 by Sacred Fire

[Kaphotics]

https://github.com/kwsch/PKHeX/issues/2789