Huawei routers used in Indian govt offices were found to be sending data to China. They were banned after the discovery. Wont be surprised if cellular components that are made in China send back data quietly.
I can find references to a ban based on 'security concerns' but not one that found actual evidence of snooping. I only had a brief look however. I too would be grateful to the GP for links.
Don't assume malice. This would be considered completely normal in China, both legally and culturally. You would a have hard time explaining the concept of privacy to them. This is likely not some big conspiracy.
The flip side of that argument is that the fastest way to explain the concept of privacy to a manufacturer that spies on you, is to stop buying their devices. Consumers don't need to assume a conspiracy in order to communicate their preferences.
Except they know they are exporting thus have to tailor their product to local law. The idea that all these Chinese leaks are just accidental oversights is fairly naive, especially in the light of China's industrial espionage efforts.