Sounds like fantasy. Whatever they wrote you the IOU for also comes out of your book, so your balance is $0. Doesn’t work like that.
https://tether.to/wp-content/uploads/2021/04/tether-assuranc...
IOW, "They have the total amount of CP, loans, and bonds they say they have. Whether or not the issuers of those IOUs is Bitfinex or some shell company connected to the owners of Tether we have no opinion on"
THus I am perfectly fully backed.
So the answer to your question is it would happen in crypto where there is no regulator and people trust ‘audits’ which verify nothing.
There have been precisely 0 (zero, none) completed audits of Tether's holdings