This is awesome! The game feels very responsive. Also took a quick look at the code and it's very well documented and organized. Are you in the Colyseus discord? I'd love to learn more about how you made the game and what your plans for it in the future are.
As a quick aside, have you thought about using something like https://github.com/michalochman/react-pixi-fiber to unify your UI/game rendering into a single declarative React tree?