Its pretty widely believed that the Chinese government can and has accessed Chinese Citizens' iCloud accounts before [1]. (I work at Google).
[1]: https://www.theverge.com/2018/7/18/17587304/apple-icloud-chi...
[1]: https://www.theverge.com/2018/7/18/17587304/apple-icloud-chi...
That is, China sets up elaborate domestic surveillance, deep packet inspection everywhere, asks citizens to install apps which backdoors their phones to scanning and logging, and all you need to do to thwart it is buy an Apple device? Does that sound like something they would willingly permit?
That would be like the US congress passing a law requiring Key Escrow, and every device manufacturer on the market complying, but if you just buy a Xiaomi phone, you can bypass it.
How likely do you think there's no special alteration to how iCloud encryption works in China?
https://www.amnesty.org/en/latest/news/2018/02/5-things-you-... When Profits Threaten Privacy – 5 Things You Need to Know about ...
But also removing the VPN software.
https://www.ft.com/content/ad42e536-cf36-11e7-b781-794ce08b2... Apple drops hundreds of VPN apps at Beijing's request