I've read through the reproductive rights section of the report but only some of the citations, and I'm still looking for the interviews.

The OHCHR report does cite Zenz in citation #140 a few times, on page 19 and continuing into the footnote on page 20 of the pdf.

Citation #140 is for a statistic that in certain counties 10–20% of the adult "ethnic population" (the report's words) were detained.

The footnote mentions Zenz's name twice, but also mentions Xinjiang Police Files, which is Zenz again.

I'm still looking for the 40 interviews. It would be really interesting to hear what they have to say. Speaking before seeing them, I'm not sure I can have full confidence in them when I'm aware of so many instances where western governments and their allies have produced false witness testimony to justify foreign policy, e.g., the Nayirah testimony before the Gulf War, witness accounts of Iraqi WMDs before the Iraq War, fictitious witness accounts of a genocide in Libya before the NATO bombing campaign that obliterated the country, and a large number of North Korean defector testimonies that have fallen apart under scrutiny, as reported by the Guardian. This is how consent is manufactured. America is engaged in a trade war with China and hostilities are escalating in the South China Sea, and these activities require consent from legislators and the public. But I'm not going to discount the interviews either — it's evidence that has to be stacked up with other evidence and then appraised as a whole.