React 19 Removes PropTypes Entirely - Runtime Checking Alternatives

It continues to run identically, since prop-types is an independent package unaffected by the React version

React 19 removed PropTypes support from the react package itself; a propTypes static attached this way no longer runs at runtime regardless of the prop-types package still being imported, and TypeScript, zod/yup at boundaries, or the standalone prop-types package are the remaining validation options

PropTypes validation now runs at build time instead of runtime, throwing a compile error for invalid props

React 19 automatically converts propTypes definitions into TypeScript types during the build step