Any exchanges accepting and trading Tether should be considered fraudulent.
Yes, I understand the "problems" with Tether, but it has objectively succeeded in holding up its market price of ~$1 USD for more than a couple years now, so it has functionally served its purpose to its customers needing to make short-term exchanges. To a great degree the fact that the black box's inputs and outputs work is all that really matters, not what's inside the black box.
Might it implode one day? Maybe -- that's life in a financial anarchy. But that should be part of your model. For example, minimizing the time you hold USDT and using it purely as a medium to facilitate other transactions reduces your risk.