China's in over its head. They got somewhat of a trade deal, though they never had much to bargain with because their economy is much more dependent on imports than the US economy. So, their trade deal can't have gone as well as they would have liked, so they were always going to be unhappy, no matter what they got. They won't be happy, even though they plan a signing photo op come January.
Beijing-rooted leaders in Hong Kong are genuinely confused about the public outcry. In all likelihood, the Chinese truly don't know how much they afflict and oppress their own people. Because they are out of touch with normal life—because they rely on inhumane means to silence any opposition—they probably believe dissidents are genuine misfits. Beijing remains oblivious to how cruel and rightly despised its rule is. Had Beijing even tried to know what real, ordinary people really, truly think, they might not have been surprised by Hong Kong's harsh rejection. But, Beijing never cared enough to try to ask in the first place. So, Beijing despises Hong Kong, all the while doing so under the delusion that its spite is well-deserved.
The British have politely demanded that Beijing honor the 1984 Sino-British Joint Declaration and hold talks with Hong Kong protestors. From Beijing's perspective, this is as unimaginable as a Chinese demigod being willing to hold a dialog with a cockroach. Make no mistake, Beijing does not feel that Britain is making any kind of request; it is purely interpreted as an insult, like demanding one to kiss one's own rear end. However incapable Beijing is of understanding the polite demand, let alone obeying it, the demand remains legally binding. Britain is building a case for nullification and Beijing believes that every way out is an illusion meant to insult.
Then, there's Huawei. The trade agreement China holds no cards to oppose with won't matter. Huawei needs customers and Europe is skittish, to say the least. Huawei needs money because the Chinese government needs money. Central planning squandered loans on enormous, countless, empty buildings. The concept of "scalability" is foreign to the government that always gets what it wants, until it can't afford to anymore. Even then, the Chinese won't know why they can't afford to anymore because they can't understand "scalability". Huawei's losses will weaken China's position further when it comes time for round 2 of the US-China trade negotiations.