The main earlier claim was the 2020 Libya / Kargu-2 story.
In 2021, a UN Libya panel report said Turkish-made STM Kargu-2 loitering munitions / lethal autonomous weapons systems had “hunted down” retreating Haftar-affiliated forces and were programmed to attack without needing data connectivity to the operator — the famous “fire, forget and find” phrase. The ICRC casebook summarizes it as an autonomous weapon that might have been deployed and targeted fleeing fighters.
But that Libya claim had the same problem: it was not explicit proof that an autonomous drone killed a human without human supervision. The Lieber Institute at West Point noted that the UN report “does not say for certain” that humans were killed by such systems operating without human supervision, even though media treated it as possibly the first autonomous-robot fatality.
The Bulletin of the Atomic Scientists made the same distinction: if anyone was killed that way, it would likely be a historic first, but the UN report implied rather than clearly stated it