react/no-function-default-props

React 19 ignores defaultProps on function components. This rule reports an assignment only when its target is statically proven to be a function component returning JSX.

function Button({ size }) {
  return <button data-size={size} />;
}

Button.defaultProps = { size: 'medium' };

Use a JavaScript default parameter instead:

function Button({ size = 'medium' }) {
  return <button data-size={size} />;
}

Class component defaultProps and unproven objects are not reported. No fix is offered because safely rewriting destructuring, rest props, and public types requires project-specific intent.