Tether has been extremely opaque in what assets they hold to ensure the 1:1 USD/Tether peg. It's been observed that at least as one point they definitely didn't have enough USD-equivalent for it, and they've been issuing new Tether at quite a clip since then with flow on effects to the BTC market.

Now if they actually had this financing in place, this would all be fine - but nobody can find a proper accounting of who they're doing business with at the scale they claim to be doing business, beyond the observation that none of the big US players seem to have any business with them - so what assets are actually backing tether?

https://www.forbes.com/sites/nicholasgans/2021/05/13/tether-...

Note that the vast majority is "commercial paper": basically short term loans to companies with relatively risky backing. The problem is that's all we seem to know: no one knows from who they've been buying these. It might be large US companies with 50 year histories, or it might be Chinese property developers at risk of bankruptcy (at which point international debtors will be the first to lose their money).