Due to the changes in contextual/bidi validation, Windows’ client APIs dropped the additional context/bidi checks with IDNA2008 to forward-proof ourselves against other contextual/bidi rule changes. As our APIs are intended for client side use, we expect that labels invalid by the rules would fail to be registered, so we’re depending on the existence of a DNS record to confirm whether that’s valid or not. (Eg: we’re depending on the registrars to do the contextual/bidi validation when registering domains).