This mini-thread is about USDC.
From what I can tell, unlike Tether USDC haven't publicly disclosed what proportion of their reserves are backed by treasury bills and what proportion are stuff like commercial paper - just that they're backed with a mixture of both. On the other hand, they do claim that everything backing their token has very good credit ratings and I don't think Tether do.
Bank customers money are backed (up to 250k for each account) by the US treasury though which is a pretty significant difference. The US can print itself out of any bank run, at least in the short term.
Compare to the capital ratios of your average bank, though.
[1] https://www.coindesk.com/tether-first-reserve-composition-re...