Summary for newbs:
Bitfinex is a crypto exchange kinda based in Hong Kong and kind of based in Taiwan (this seems to change depending on convenience.) Taiwan recently started becoming more rigorous about monitoring international USD wires, and lots of Bitfinex users had their money stranded in Taiwan. Bitfinex stopped supporting US customers because of these difficulties (AFAIK most customers did eventually get their money out though)
Tether is a company/product that is a cryptocurrency that (aspirationally) has a value of exactly 1 USD. The Tether company and Bitfinex are (supposedly) two unrelated companies that nevertheless have mostly the same people employed as principals. Because crypto daytraders need easy ways to quickly pull their money in/out of crypto exposure, the Tether currency has been a massive hit as a way to convert into pseudo-dollars. Because of this, people have bought billions of these "tethers" from the company, but no one has a good handle on where these billions of dollars are safeguarded, if at all.