If you wrote what you had in HTML and ran it through a validator it would report:

Error: Named character reference was not terminated by a semicolon. (Or & should have been escaped as &.)

Most HTML parsers perform a lot of error recovery. JSX is not so forgiving. The semi-colon on the end of a character reference is mandatory:

<p>&copy;</p>

Alternatively, just use a copyright sign directly:

<p>©</p>

You can use © for the copyright symbol in React component.

function Footer() {
  return (
    <footer>
      <p>&copy;</p>
    </footer>
  );
}

use this tag it works event i used the same in HTML: &copy in JSX : © or direct ©