That's not an audit, it's an attestation. The article says:
>The company does release quarterly attestations, separate from a thorough audit, as required by a 2021 legal settlement with the New York Attorney General’s Office. Following the hiring of its new accounting firm, BDO Italia, earlier this month, Tether said it intends to release them on a monthly basis, beginning early next year.
https://blockworks.co/tether-pushes-back-timeline-on-audit-r...