Ok, so it's either that I've never noticed this, or it's a new bug, but the glow squids and the normal squids seem to not move very smoothly. Their movement is sort of glitchy. This also makes the squids be able to go out of the water a bit and then seem to teleport back into the water. I don't think this was intended because it just looks a bit off. I'll test this with other versions to see if it's just for this snapshot, but for now, I think it's a movement bug for the squids in snapshot 21w03a.