Oversight of Law Enforcement Surveillance Act of 2021 This bill establishes reporting requirements related to the use of surveillance technology by law enforcement agencies in major metropolitan areas. The term major metropolitan area means an area with at least 250,000 residents. Specifically, the bill requires a law enforcement agency of a major metropolitan area receiving federal funds from the Department of Homeland Security (DHS) to report annually to DHS, the Inspector General of DHS, and Congress on the use of surveillance technology. Additionally, the bill requires the Inspector General of DHS to report annually to Congress on the use of surveillance technology and the impact of its use on civil liberties and privacy.