Aren’t the people they are imprisoning criminals that broke the law? For perspective, the US has 2.2 million minorities in prison.
The situation in Xinjiang is therefore much worse.
Most of the people concerned should not be locked up anyway—think of people who can’t afford to pay fines in the US, or people who pray in Xinjiang. It is extremely rare that a population is so poorly socialised that it is necessary to imprison over a tenth of the population. Perhaps they are in some strict sense “criminals”, but China can choose who to criminalise (as can the US), and it is clearly making unhelpful decisions.