Except for this one I could agree with your provided list, bittrex has a very long history of issues since 2017-2018 and they just continue creating problems for their users, just searching for Bittrex whether on this section or on "Exchanges" section you can find many people that had issue with this exchange which is mostly about KYC.

You could say they have a tendency towards asking their users KYC whenever they want based on nothing, and I don't even think it's random and I think it's based on how much money you got on your balance, the more you got on your Bittrex account the more chance of them asking you for KYC or in worse cases even source of fund.