Runway Entrance Lights at intersection J/4L which is where the incursion happened. These are taxiway centerline lights, and should have been red at the time. Here's the gotcha: REL only illuminate once the departing aircraft reaches 30 kts. https://www.faa.gov/air_traffic/technology/rwsl/pet/

Based on the animation https://twitter.com/CaseWade/status/1614342894248394752 at 00:14, I'm pretty sure AA 106 was no longer in visual contact with REL lighting by the time DL 1943 reached 30 kts.