This has been the status quo for a while. China is very sensitive about Taiwan. There have been several spats between China and airlines in the last few years; for example, <a href="https://www.businessinsider.com/united-airlines-makes-concession-to-recognize-taiwan-angers-china-2018-8" rel="nofollow">https://www.businessinsider.com/united-airlines-makes-conces...</a>
Had a hard time parsing the title for some reason. So what happens is that the people validating apps for the store look for parts of the application where the user has to select their country. If they find that Taiwan is listed as a separate country instead of a region of China, they refuse the app.