Of the three companies named:
- Google's user-facing services (search, email, app store, docs, ...) are blocked, but Google Ads (which are censored) and Android (which comes without any content that would require censorship) are still sold.
- Microsoft: I'm not aware of any of their products being unavailable. Windows is the dominant desktop operating system in China, and I'd be surprised if the app store wasn't censored. Bing search results are definitely censored (they tell you so at the bottom of the page).
- Amazon isn't selling much that could run afoul of censorship, except possibly books (remember when Amazon used to be an online bookstore?) but in China their market is mostly targeted at the niche of high-end imported goods. (Note the country-of-origin indicators on https://www.amazon.cn/ )
I was telling my friends who moved from China and kept their iPhones, to just buy a new one... just in case...
These are just changes to the app catalog, what reason do we have to believe that a bunch of brain training apps being dropped or withdrawn is evidence of censorship? Has any of this been verified with the App publishers?