Yeah there’s already at least one well known case. This article mentions it wp.api.aclu.org/press-releases/208236

The use of facial recognition technology by Project NOLA and New Orleans police raises serious concerns regarding misidentifications and the targeting of marginalized communities. Consider Randal Reid, for example. He was wrongfully arrested based on faulty Louisiana facial recognition technology, despite never having set foot in the state. The false match cost him his freedom, his dignity, and thousands of dollars in legal fees. That misidentification happened based on a still image run through a facial recognition search in an investigation; the Project NOLA real-time surveillance system supercharges the risks.

“We cannot ignore the real possibility of this tool being weaponized against marginalized communities, especially immigrants, activists, and others whose only crime is speaking out or challenging government policies. These individuals could be added to Project NOLA’s watchlist without the public’s knowledge, and with no accountability or transparency on the part of the police departments

Police use to justify stops and arrests: Alerts are sent directly to a phone app used by officers, enabling immediate stops and detentions based on unverified purported facial recognition matches.