Mystery bit appears beside my steering wheel

[Nissanman2022]

Got in my car tonight (not quite Halloween!) and spotted this small round disc with a red light attached to a wire coming out of a strange place in the trim beside the steering wheel. I’ve never seen it before. It was just dangling in mid air. Given I had been in hospital the previous day after an accident when I was knocked unconscious I feared that I had gone mad. So I took a few pix which suggest the object is real. Can someone please explain?

[kt53]

If you use Facebook post this in the Nissan Pulsar C13 Owners Club group. There is very little activity here now as most have migrated onto that group. I have no idea what that is.