Hong Kong is now in the legal jurisdiction of China (I think) - the UK returned it to them...
The Chinese government seem very volatile about cryptocurrency markets (sometimes they hate them, then bitmain starts to move and they get worried and bring them back or whatever happened)... I have to sayt my issues with bybit were that it doesn't have the litecoin/bitcoin pair and it's very over advertised to the point where they may find it more profitable to exit scam than people trading (they also don't display the fees they'll charge when you make an order on their site which has started to greatly annoy me).
Bitmex has it's issues, I'm not sure what yours were or if it's just being in the US but sometimes things didn't work properly - you get liquidated too early and whenever you try to put in a trade when it's volatile or even just moving a bit you start to be unable to place orders...
I spotted there was a release of a decentralised leverage trading exchange on this forum but I didn't get chance to take a look at it, it seems that decentralising or adding more servers is the way to go for bitmex so maybe once they've evolved a bit the decentralised exchanges will be better but no one seems to make a DEX mobile app.