Apparently there is a PRC smear campaign against Adrian Zenz - mandiant.com/…/pro-prc-information-operations-cam…, including by creating what Mandiant describes as what they “suspect to be at least three fabricated letters based on obvious grammatical errors and typos” to smear him - so I’d take anything that is ad hominem attacks against him rather than debating his actual work with a grain of salt.
However, even if you don’t accept his writings, there are plenty of other people who have done credible research into the plight of the Uyghur people - e.g. resources contributed to xjdp.aspi.org.au, such as articles like this one by Gene A. Bunin: livingotherwise.com/…/the-elephant-in-the-xuar-ii….