The same thing always happens when we combine the words "disappears" and "X amount of money" in the same sentence. Nothing has disappeared, those funds have simply changed from one portfolio to another (or several) and hands of course, and in this case with the connivance of Justin Sun and his silence, a silence that says a lot, unless Sun makes a statement about it later, but I doubt it.
I have never liked the idea on which USDD is based since we have seen similar disasters before, but if they also try to silence things and the people who should give explanations remain silent, the problem is bigger and more serious.