I'm unsure who and why usdt crashing and I think therecould be reasons like:
- market manipulation with fear and panic
- some insider made a move before SEC taking move on Tether which they have been eyeing on for some time
- stablecoin contagion affecting USDT, and panic driving the volatility further on USDT de-pegging
Usdt de-peg happened in last bear market too so it can be normal but I'd not rely on tether for my holdings.
Chart Source - Coinmarketcap.com