Name and explain the two major concerns voiced about Tether.

The fiat-collaterized token Tether is said to be backed 100% by USD. However, eventually it became clear that this surely was not the case making Tether not transparent. Bitfinex is not an open protocol and if too many people want their USD back at once, a bank run can happen (unregulation). Tether could just be printed extra without people knowing which make it a risky token.