Can someoen explain this to me.

So i was playing aram as yasuo and i had a Katarina on MY team. At one point in time the other team killed me and where it said that jhin got an assist on killing me under his tab it said bouncing grenade which is his ability, and at the very bottom it said bouncing blade which is katarinas q. I have a picture of it if needed but i was just wondering how or why katarina came up as an assist to my death if she was on my team