You need to distinguish that UST and USDT are not the same thing at all, UST is an algorithmically stable coin backed by other cryptocurrencies, so it will crash when the market drops, while USDT is also backed by USD and some other assets like bonds...
The collapse of UST caused panic but the stable coin market is still very active, many blockchains are making their own stable coins, despite the recent collapse of UST.
https://decrypt.co/104642/defi-aave-stablecoin-gho