Slay Belle Katarina lost her unique Q particle.
Judging by her rework on the PBE, Slay Belle Kat lost her Q particle, while her Project skin still has a new particle (Although the project skins are on a different tier). I know its nothing too big, but many skins have lost small features like this and had them reinstated (i.e. Steel Legion Garen's E particle). I also understand that it's an entirely new skill, but just give it some snow falling or something, the particle is the main reason I bought the skin.