That is pure FUD. In the last year there has been less than one tenth of a cent of movement. It is so stable the graph is incredibly zoomed in to show any movement at all.
[0] https://fortune.com/2021/10/15/tether-crypto-stablecoin-fine...
[1] https://www.bloomberg.com/news/features/2021-10-07/crypto-my...
That aged well. Tether hit $0.9935 hours after this comment.