That looks bad. The worst previous fall of Tether/USDT was down to about $0.90 in mid-2017, during which it was substantially below $1.00 for over a month
That is uncertain, because the degree of entwining has always been unclear. News reports 5 years ago also contained a lot of worry about Tether's risks, maybe even more than today.
What was obvious 5 years ago, and remains unchanged today, is that Tether claims to represent an enormous amount of money, which is a difficult hole to fill if Tether turned out to be far from fully-backed, as many suspect