Is that even legal?
The problem here is that Bittrex threatened to charge 20 USD per month if users don't withdraw their assets. If the amount is too low, it's impossible to withdraw, but they will still charge you 20 USD per month for not withdrawing. They also admit that they know it's impossible for us to withdraw and avoid the fee:
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As of today, 4 January 2024, default fees will be charged automatically on your account, in accordance with applicable laws. The amount will be determined based on costs incurred by Bittrex Global in maintaining assets in default on the platform and will be reviewed every six months. Initial fees, which will be incurred from today, will be set at a rate of 1% per asset per month, with a minimum charge of up to $20 per asset per month.