I know privacy-conscious people who'd wipe their devices before and after entering China, but now it seems the surveillance is even more aggressive.
If you enter Xinjiang across a land border they put spyware on your phone.
https://www.theguardian.com/world/2019/jul/02/chinese-border-guards-surveillance-app-tourists-phones
@michel_slm yummy, nothing like a good dose of malware before gling to xinjiang.
They bring it into another room, and considering other things I have heard, I wouldn't be surprised if they are also embedding hardware, somehow.
At least with this software, wiping before going and after returning is a possible solution.