The btc withdrawal issue is bad, one tx unconfirmed for 4 days now, and a new one was sent with a very low fee as well:
Fees 0.0000168 BTC
Fee per byte 6.747 sat/B
While the withdrawal fee is 0.0004 btc on your website.
This is a real problem right now, please fix this!
Ok both transaction confirmed, still 4 days is way too long to wait!
I agree. The customer pays 40000 sats and Bitmain only uses 1680 sats to pay the fee. This is outrageous. Do you happen to know which pool finally included the block? Chances are good that it was one of Bitmain's pools. If so, they got to pocket the whole 40k sats and you got to wait four days. This makes Walmart's lines look like a customer service dream in comparison.

None of the blocks was mined by Antpool, but it's urgent, this should be fixed, I was about to pay $18 to accelerate the transaction with another pool.
They should charge some fee extra as they have to move your coins into cold storage. However, I don't see why companies like this can't use dynamic fees or ask people to manually se their own fees themselves (with a recommended fee as an autofill)...
Indeed dynamic fee would be the best solution to use, they should use fee estimation built in bitcoin core (estimatesmartfee).