See:

• The Wartime Repressions Reports of the Russian human rights defence group OVD-Info
• The reports of the SOVA Research Centre
• The May 2023 report of the United Nations High Commissioner for Human Rights (OHCHR)
• The International Federation for Human Rights
• And these overviews by *Politico,* Amnesty International (AI)—here and here--Human Rights Watch (HRW), and Wikipedia.