I did find a reference to this type of behavior...from 2010.
What I suspect happened is some very old security code accidentally got compiled into the Facebook server app, in relation to the company's new security feature, and I just happened along when it was exposed.
Either that, or I stumbled into a time vortex.
I treated myself to a new smartphone today. Among the apps I loaded was Facebook. I had copied my password from Dashlane and was ready to go, when I ran into something new:
Facebook's new security system.
To prove I am who I am, Facebook displayed a set of images, each with a set of names, and asked me to pick the person who matched the image. OK, this ought to be good.
The first was an obviously 30+ year old photo of a chubby baby. So who is it?