Tether announced a hack in which they lost 30 million USDT, not USD. As they don't plan to redeem those USDT to USD, in no sense Tether lost 30 million USD. As far as I can tell, Tether lost nothing.
That is, of course, if it actually was a theft, and it was actually for $30 million. It's a single source currency, no one but the people running Tether knows what's actually behind it.