We have confirmed the recent token outflow from Bittrex is due to the termination of orderbook partnership between Bittrex and Upbit. Upbit's funds previously held in Bittrex wallet have been moved to Upbit's new wallets. The new wallets will be updated and reflected in our system soon.
We have added the stablecoin Tether (USDT) to our Exchange Deposit Tracker!
However, please note that we are only tracking USDT in the form of ERC20 token, which represents only 7.5% of total supply. Majority of USDT tokens are issued on the Omni platform, which we do not track currently.