This sounds like a clear-cut case of a violation of academic ethics to me - if he’s willing to steal work from you, how could anyone trust anything he’s ever published? I’d strongly consider going to talk with the head of your faculty, school, or department, depending on how your university’s hierarchy is structured, so that the university can begin academic integrity proceedings against him, and I’d also consider talking to the university’s lawyers about what your legal options to dispute the patent are, and if you would be able to file one in the UK.

China does not have a good history of enforcing IP rules. This is a widely-covered topic (Stanford legal blog summary, CNBC study, google search on the topic). This topic has been a focus in recent international politics, as IP has been a non-insignificant focus in larger trade talks. While President Xi has claimed that he's cracking down, things still aren't that great.

To that extent, you're simply now experiencing pain that many others have felt. Unfortunately, there aren't many resources available for you to remedy this problem.

As you say that your advisor works for a UK university, you might be able to do contact the UK university and see if they can assist in policing this in some way. It is unlikely they can for the patent to be overturned or rewritten to acknowledge you, but there may be some other pressure they can exert on the professor. Similarly, if anyone tries to claim rights to your invention outside of China, it's highly likely you could claim prior art.

Lastly, while certainly suspicious, I wouldn't take it as proven that your advisor was responsible, at least not based on what you've written.

Legally, you don't need to do anything, you lost nothing and don't need to worry.

Ethically, well, others answered that adequately I think. Obviously it's not ok, but you don't even know for sure your advisor was involved. I would just like to add that you should keep in mind the cost to yourself of taking any action and whether you really want conflict in your life when you aren't actually threatened.

Details about the legal aspects:

In general, getting a patent is meaningless. The patent registry does some research to verify validity, but only as much as their fee pays for. States don't enforce patents in general, so the people who filed the patent would need to sue you. Then you would trivially win, because I assume you had your thesis published in a reputed place which can vouch for the publication date and it's such a blatant copy (which thus isn't novel, and that's the basic requirement for patents all over the world).

You yourself couldn't get a patent on the idea anyway (in most countries), because you published your paper and thus destroyed novelty (yes, patent law really works like this - you need to file for a patent before you publish anything).

Next, Chinese patents only have any effect in China even if they are legal and enforceable in (Chinese) court. Because of the exorbitant cost of patents and the questionable enforce-ability in China, you probably don't want a patent in China anyway unless you are Chinese or otherwise based there.

If, next time, you wanted to get a patent yourself you should talk to your university early on. Often they will get a patent for you (but also own the patent) or help you get a patent (depending on your contract with them).

(I passed a 2ECTS course on intellectual property at a good university recently, but that's all of my credentials)