China just enacted a law criminalising a range of protest-related activities in Hong Kong and allowing for extradition to the "mainland". So far today, 180 have been arrested and pro-democracy groups have started shutting down, having been essentially criminalised. (Although it's also because this cut their overseas funding off too.) One analysis that I read noted that China promised 50 years of freedom in Hong Kong following the transfer of sovereignty. They've given just 23.
China doesn't need Hong Kong to be a gateway to the rest of the world anymore, so they're bringing it under their control as a show to the population at large that there is no dissent permitted.
I visited Hong Kong in 1995 and there were a lot of people there dreading the impending handoff from the UK to China. I visited again in 1997 and the attitude seemed to be "well, ok, this isn't as bad as we thought". It's gone so far down now. It's very sad.
China is unhappy with the UK offering residency to eligible HK'ers Even by China's poor standards, this a bit beyond the pale. Put aside the fact that those 3 million eligible were former British citizens still holding corresponding passports. The UK is a sovereign country and can offer residency or citizenship to whomever it pleases. It's not as if mainland Chinese nationals don't already take advantage of this. When grilled about the concentration camps in Xinjiang, or any of its other nefarious activities, the CCP cries "It's our internal affair. Mind your business." The hypocrisy. But hey, when facing the prospect of losing a third of HK's citizens, probably the richest and most talented third, it's understandable they would be unhappy. But what can they actually do to stop people flying out of HK? Pandemic travel restrictions are currently on their side, but then what?
Possibly. Mainland China already makes it exceptionally burdensome to send money out of the country, especially if you're a foreigner. But HK's economy is built around a robust and free financial sector. If the CCP were to introduce those types of regulations, they might conflict with the corporate oligarchs that control the territory -- people much more powerful than the pro-democracy protesters in the streets.
Those oligarchs largely aren't the ones they need to worry about fleeing. China isn't thinking about what value HK has had in the past, they're thinking about how it will be most useful to them a decade+ from now.
It's not that the oligarchs themselves would want to flee, necessarily. It's that they would be opposed to financial regulations interfering with their globalized businesses. The CCP needs their support to control the territory.
I'd imagine that with the growth of China there are more future opportunities for them in closer ties to the mainland than there are overseas, especially since most of Hong Kongs success in the past came from it being seen by the world as a gateway to China, something that is increasingly becoming unnecessary.