China has the least effective vaccines and limited research evidence on their performance. They are simply not in the same position as even other wealthy Asian countries.
HK is a risk to the mainland because we have more international links and 2/3 jabbed with a good vaccine so higher chance of being asymptomatic in the off chance carrying the virus.
Politics is a convenient cover for the lower efficacy of Chinese vaccines.
To be fair, it makes sense that the UK or any country would report it. We are in this mess because countries chose to ignore it. Once the WHO declares this over, then its fair for that to change.
On a side note im interested to see how china opens up, and how the rest of the world treats it. Im no scientist, but 1 billion + with low levels of natural immunity would have to provide some incredible kindling for mutations. Hopefully we dont see any game changers, like we did with Delta.