However, I am surprised that they just disappeared with $11,000 so easily. I didn't even think that this was a sufficient amount to create and develop such a project, especially since they have been working for about a year, judging by the information on the monitoring.
Have you considered contacting Tether directly and requesting a refund through them?
There is a form for reporting such cases.
https://cs.tether.to/TRAs it is not a small amount, if you already have to give someone KYC data, at least let it be an officially registered company. And let them explain with Whitebit who is the owner of that $11k.