A few months ago I wrote a post about how to spot an exchange that was in danger, by looking at the withdrawal fees, and Bittrex was flagged using this approach.
Here is the article: https://steemit.com/bitcoin/@teatree/beware-withdrawal-fees-on-exchanges
It now looks like something is up, because Bittrex is behaving very oddly.
Accounts disabled
Thousands of users have had their accounts locked in the last few days. They seem to be legacy accounts which should have been grandfathered in, but Bittrex are requesting they upload passports and photo IDs if they have just $1000 in the account.
This can't be anything to do with KYC/Money landering rules. Those focus on deposits and withdrawals of more than $2000 a day.
Here is an example from Reddit:
The owner of the account was Australian.
Delisting popular shares
They're also delisting heavily traded coins like Bitshares. There was some speculation on bitcointalk that this was because they are under the cosh from American authorities over coins that have had an ICO.
Trying to prevent withdrawals
They have also reduced the amount people can withdraw. Unverified accounts created before August 2017 are now restricted to a withdrawl of 0.025 BTC a day - even though legacy accounts were supposed to be grandfathered in.
Combine that with a very high withdrawal fee - 0.001 btc, which is $5.50 at the bitcoin price of $5,500, and it's clear they don't want people withdrawing coins.
In fact their response to the bitcoincash fork, which credited the BCH immediately, was designed to prevent people withdrawing their coins prior to the fork. Whereas exchanges like Poloniex and Coinbase told users to withdraw if they wanted the free coins, as they weren't sure if they were supporting BCH.
Exchanges trying to prevent withdrawals are a big red flag. If you have a lot of coins on Bittrex, consider moving them. And do it in small amounts - looks like large withdrawals will get your account locked too. Consider buying steem or doge and withdrawing that to avoid the hefty fees.