When a user selected the preferred language I save it in a cookie NEXT_LOCALE.On the index page / the NEXT_LOCALE cookie knows to redirect the user to the preferred language but if the user comes from an external link like email or newsletter like apple.com/startup it doesn't redirect the user to the preferred language. Is there a way to do this without affecting the SEO?

//next-18nnext.config.js

module.exports = {
  i18n: {
    defaultLocale: 'en',
    locales: ['en', 'fr'],
  },
  react: { useSuspense: false },
};

===============UPDATE===============

My language switcher and setting the cookie:

const LanguageSwitcher = () => {
  const router = useRouter();
  const { locale, pathname } = router;

  useEffect(() => {
    if (locale === 'fr') {
      document.cookie = `NEXT_LOCALE=fr`;
    }
  }, []);

  const activeClass = (lang) => (lang === locale) && 'active';
  return (
      <>
        <Link  href={ pathname } locale="en">
          <LanguageLink className={ activeClass('en') }>
            EN
          </LanguageLink>
        </Link>
        <LanguageSeparator>
          |
        </LanguageSeparator>
        <Link href={ pathname } locale="fr">
          <LanguageLink className={ activeClass('fr') }>
            FR
          </LanguageLink>
        </Link>
      </>
    );
};

And in my _app.js

 const languageCookie = getCookie('NEXT_LOCALE');

  useEffect(() => {
    if (languageCookie === 'fr') {
      router.push(`${languageCookie}${pathname}`);
    }
  }, []);

But with this implementation, the page loads for a second on 'en' then redirects to the cookie language

Should I take the cookie in getStaticProps from each page?

Please let me know if I should share more code or any other information.

Thank you!