Seems like Tether does not issue a compliant coin afterall. USAT is issued by Anchorage Digital Bank

Tether owns/licenses the USAT branding and collaborates on the product, but Anchorage's disclosures expressly say Tether has no obligation to issue, redeem, or guarantee USAT. USDT, by contrast, is issued by Tether International, S.A. de C.V., an El Salvador company.