Inertia - Can't find variable: React

My Inertia app uses React 18, which shouldn't require explicit import React from "react", as they made it obsolete in React 17. But for some reason, when I don't import React in my files using JSX, I'm getting this error:

Can't find variable: React

Do I need to add something to the config? I checked and it's using React 18 for sure.