Earlier quoted context omitted.
IIRC china invited many nations to xinjiang, not just muslims but some western-aligned countries too. The muslim countries and said it was fine and no major mistreatment was going on, while I believe some western countries refused to go, claiming some sort of taint. So if you believe something, then you get invited to see what's going on, and you refuse, what does that say about you? It's the makings of a thought bub…
It's very, very hard to know what's really going on in a totalitarian / authoritarian country, even when they let you in and explore unreservedly. Famously, the Red Cross inspected one Nazi concentration camp and gave it the thumbs up: https://en.wikipedia.org/wiki/Theresienstadt_Ghetto_and_the_... Needless to say, there was nothing good about that camp, or any of the other ones.
Second, I agree there's a capability of falsification from either side, be it china or a news outlet. But neither does it translate to guilt on either side.
In the absence of such you'll have to consider from the first principles, and you'll find the US/west/people involve have a lot more incentive to keep china down. As such the better entities to trust are the third parties, ala the muslim states.