Peeling
In the mid and late game, your clearest job was to peel Xayah, but you kept spending key spells on the wrong targets or at the wrong time instead of holding them for the enemy dive. The Wizzy repeatedly wanted you saving Q and W to stop Jax, Jarvan, Ryze, or Ezreal from getting onto your backline, because Cho'Gath's value in these fights comes from locking down the first engager and denying counterplay. The practical adjustment is to play a step behind your carries, let the enemy commit first, and then chain your silence and knockup to interrupt their engage before they can reach Xayah or force her to burn cooldowns early.