https://ag.ny.gov/sites/default/files/2021.02.17_-_settlemen...
Tether wasn’t backed at all times. The argument was that this happened due to asset seizures in Poland and Portugal in 2017-2018.
https://www.theblockcrypto.com/post/95207/bitfinex-tether-ne...
Seems to me they couldn’t prove malicious intent, so they suggested they stop trading. Frankly this seems a bit of a click-bait title with the whole “illegal activities”.
Sure, tether wasn’t backed at all times (probably is now), due to governments seizing their funds. Also banks do this all the time, every time they issue a loan for instance. The bank only keeps 10-30% collateral on your home.