Thats not face recognition but the proximity sensor (so the phone knows when to turn off the screen wenn its near your ear or in a pocket)
Deactivating it should theoretically be possible, but I don’t know how and wouldn’t want to
I had similar experience on pixel 5 with flickering tiny dot of light which was indeed the proximity sensor. In my case it was a Telegram Setting > Chat Setting >Raise to Speak. Toggled off it stopped it.
Thanks for your responses!
Indeed, it’s apparently the proximity sensor, but a very strange one. All others I have seen in the last 13 years on smartphones worked only with (invisible) IR light. Why this one uses (partitially) visible light…?
I was also surprised with the moment of activation… When call in progress; sure, the display turns of as excpected, but after power on it seems not to do anything.
Anyway, thanks again.