As with the Uighur issue in China it’s really simple: we assume the worst wherever independent media isn’t allowed to report.

It would be very easy for the Chinese authorities to allow critical media in every province just like it would be easy for Russia to have OSCE (or equivalent) inspection of “excercises” near the Ukrainian border.

Questioning sources and rumors is a good thing - but in cases when the sources are scarce because they are denied, one should assume the worst from the party refusing oversight. This is a plausible rumor.