Tether claims to have finished liquidating their commercial paper as of a couple days ago. https://twitter.com/Tether_to/status/1580601123026501642

Chinese commercial paper had a large wave of delinquencies earlier this year (https://www.reuters.com/markets/rates-bonds/china-commercial...). The chances of Tether's holdings having zero defaults amongst all of that is... low.

Tether has an easy fix here: release the "frequent professional audits" they claimed on their website as far back as 2015 (https://archive.ph/mVPmL). They've provided various excuses and called attestations audits for nearly a decade now; their credibility is shot.