since 2018 I have been a member there for a long time and have never experienced this. and keep it safe under control.
Verified member (highest level possible) at Poloniex and Bittrex from 2017, but that didn't stop either from at times blocking my account and/or just delisting wallets without notifying me.
Just because they haven't done anything to you doesn't mean they won't down the line.
They're both great services and pretty much reliable (I still use Bittrex occassionally) but the moment you're done with them, best keep your Bitcoin on your own wallets. Just not worth the risk leaving it to chance.