The large exchanges were shown to have a signal chat group to coordinate activities. Total illegal collusion in any other financial institution but hey crypto is the Wild West. Not that outlandish to think they collaborate when necessary.

Oh there's a lot more to it than chat groups.

Bitfinex loaned money to Tether. On the loan contract, three people, we'll call them AB, CD, and EF, signed the contract on Bitfinex's behalf.

On the other side of the contract, Tether signed the contract for the loan. The three people on the loan signatories page for Tether? AB, CD, and EF.