The article does not specify which publication it refers to, but this is the only recently published report https://www.ohchr.org/en/publications/annual-report/ohchr-report-2024

During the year, a central priority of the HRMMU’s work was monitoring and reporting on the treatment of POWs. This led to conclusions that the Russian authorities inflicted torture in a widespread and systematic manner against almost all Ukrainian POWs and that many Russian POWs were subjected to torture or ill-treatment in the initial stages of their captivity. Findings and tailored recommendations fed into advocacy documents for high-level meetings with Member States, in June. In Ukraine, the HRMMU’s advocacy supported the launch of a criminal investigation by the Office of the Prosecutor General (OPG) regarding the use of torture at a transit facility for Russian POWs. The HRMMU is unaware if its reporting resulted in similar investigations in the Russian Federation. Its monitoring and advocacy also resulted in Ukrainian authorities improving the treatment and internment conditions of Russian POWs