Also, the Chinese Internet is "self-segregating".
You know how it is with the Great Fire Wall: you can't visit some outside websites from inside. Wikipedia was blocked completely in 2019.
There's actually another direction: you can't visit some inside websites from outside:
Most Chinese apps/websites are required by law to be tied to person identities. That means they have to be registered by phone number. In China, one person = one phone number. Without Chinese phone numbers, most Chinese apps/websites simply refuse to even let you use it.
There is no way to get a phone number without physically going to a Chinese phone-card bureau and present your ID card.
Indeed, it is getting difficult for foreigners nowadays to visit China. Without a phone number they can't do anything with Chinese apps, but they need that. Getting a phone number requires presenting a passport and a valid visa.
Foreign map apps are usually broken in China.
Foreigners who are not physically located within China are just trouble, from the Chinese point of view. Not only do they not want Chinese people to use foreign apps, they also don't want foreign people to use Chinese apps.
A few months ago I tried registering a QQ account. The "International" version is no longer maintained. When I tried nevertheless the last known good version, it just threw an error. The "domestic" version does not work when the phone is not physically located within China, and requires a Chinese phone number anyway.
About 2 weeks ago I noticed that Zhihu also stopped allowing you to expand long answers without an account. And of course, to register an account, you need a damned phone number. At least it allows American phone numbers.
Philosophically, I think it is the resurgence of the Chinese security mindset: Forbid all inside-outside contact by default. We have everything we need at home anyway.
Our dynasty’s majestic virtue has penetrated unto every country under Heaven, and Kings of all nations have offered their costly tribute by land and sea. As your Ambassador can see for himself, we possess all things. I set no value on objects strange or ingenious, and have no use for your country’s manufactures. --- Emperor Qian Long's Letter to King George III, 1793