Apple gave in to Beijin's requests. In a surprising move, Apple removed popular VPN apps from the Chinese version of the App Store, making them unavailable for non-jailbroken iPhone, iPad users in the red country.

ExpressVPN, Goldenfrog's VyperVPN were among the casualties.
Goldenfrog's CEO said in a blog post:

Golden Frog’s core mission is to fight for a free and open Internet experience for users around the world, so we will file an appeal with Apple — but I am not hopeful. When it comes to their App Store Apple is the judge, jury and executor, and now it appears the Chinese government is Apple’s overlord.

This removal is linked to the ever-tighter cybersecurity regulations of Xi Jinping's government, as laws were passed to force Apple and other big names to build datacenters in the country to store data domestically and make snooping easier.

Another reason is Apple's fear of having the new Apple Music service blocked in China. Such a block would be a threat to Apple's revenue.

Without apps, Chinese iPhone users can still try the manual VPN features built in iOS. Indeed, these features haven't be region-locked. The remaining question is: for how long?