A massive cache of Flock lookups collated by the Electronic Frontier Foundation (EFF) shows as many as 50 federal, state, and local agencies used Flock during protests over the last year.
Archived version: https://archive.is/20251121013626/https://www.404media.co/cops-used-flock-to-monitor-no-kings-protests-around-the-country/
For anyone else who was as out of the loop as I was, Flock is an American company that provides cameras, license plate readers, communications, and straight up data to U.S. law enforcement.