Saw a really good YT video[1] on Tether yesterday. Breaks down all the sketchiness. But the problem he mentions in the video is a problem with pretty much all stablecoins, in order to function you must have the proper reserves before generating a token, but inevatably greed kicks in and you start thinking what if you minted coins without the backing. USD pegged stablecoins are basically money printing machines in the hands of whoever runs the project.
[1]: https://www.youtube.com/watch?v=-whuXHSL1Pg