AirPods Pro 2 case sound

Randomly the AirPods Pro 2 case will make a two tone, kind of access denied, sound. This is NOT the charge sound, NOR low battery sound, NOR the separation alert. I’m not interested in “the AirPods case can make noises” We all know it can make noises.

Has anyone come across an actual answer to this sound? Based the answers I’ve seen other people have I’m guessing not even Apple are aware of this noise but surely someone programmed it in?!