It's mostly witness accounts from people they claim have been in there, frequently people the Chinese government says are terrorists. There's a natural friction

It's mostly witness accounts from people they claim have been in there, frequently people the Chinese government says are terrorists. There's a natural friction there which makes it clear that there's definitely a group unhappy with the Chinese government (and vice-versa), but it's very hard to not just devolve into outrage porn while looking around for what goes on.