A USDT coin must always have a strictly stable price of one dollar and may differ from the dollar price by only a few cents.
However, recently the behavior of the USDT and TUSD surprised me a lot. When this month there were problems with the USDT, its rate fell to $ 0 85, and the TUSD rate went up and that time was in the price from 1.1 to 1.24 dollars, which was just incredible. The rate of Bitcoin at that time increased by about 1,500 dollars by three hours. It seems that stable coins may not be stable.