Illaoi Passive Tentacle spawn bug

I just played a game as Mordekaiser vs an illaoi and i had gotten hit with her E causing tentacles to spawn around me. I was walking back to base when a tentacle started to spawn because i had the E debuff on me. I was getting ready to dodge as it was spawning and all of a sudden it immediately slammed the ground and killed me instantly right after it spawned. I was playing with a friend and he also took notice to how fast it slammed the ground the moment it finished spawning. Im 99% sure the tentacles aren't supposed to do that and that there is supposed to be a brief delay before it slams the ground like it was doing earlier in the game.