Yuumi's design is fustrating
Giving champions the feeling of killing her is just cruel, She just keeps attaching to everyone,being untargetable and removing debuffs, Healing them and giving them speed. Thats why pros ban her, she just removes counter play and does it best when their partner is smart
You know what every champion thats a yordle is frustrating to deal with like

I kinda hope that Riot makes a champion that hates yordles and enjoys killing them since he/she sees them as monsters (according to lore everyone sees yordles differently, thats why in the game they have different faces and looks).