I don't know of any specific proof, but just look at Deepin's EULA. You need to accept that pretty much all data that could be gathered will be gathered, even data like daily log in times. Stuff like that makes me believe stories that CPP is forcing companies to add backdoors. Especially when you consider that Chinese hackers are analyzing and publishing findings on NSA Linux backdoors, and releasing new backdoor malware every few months.
@CjkOvPDwQW China is a repressive surveillance state with a keen interest in spying on their own people who has conducted incredibly broad state sponsored industrial espionage.
Draw your own conclusions on whether such products are safe.
Read up on the intel management engine. It's an extra chip that was included in pretty much every intel CPU since 2008. It's got pretty scary potential, but no alphabet agency has yet declassified their info on it (think CIA denying any involvement in shipping and selling heroin, but then declassifying documents that proved they shipped heroin in coffins and bodies of dead soldiers).
You're pretty deep in the tinfoil hat zone now. CPU proprietary black box does not mean the NSA are trying to infiltrate your broken arch setup so they can let their FBI lizard agents steal ur hentai.
Oh for sure, but I'd be really surprised if the super secret black box that can't be completely expunged from your machine doesn't have anything to do with some alphabet agency.