M39 EMR and PVQ-31 4.00x = Thermal?

Operation Firestorm. It's riddled with visual bugs. BF 3 or 4 didn't have anything like that.
It only happened once... or rather, a couple of times, which I wanted to record on video. While aiming frequently (possibly only at that specific spot), the scope became thermal. I initially thought it was just a visual bug and a dark texture was simply applied to the scope, but it wasn't.
Is this a cheat? Is this a hack? No, this is BF6. Please don't ban me for this.

https://youtu.be/3t6_LQ3TH3k