The local cancer society came to my workplace to promote skin health and one of the items was a small camera system. You put sun block on one part of your face, stuck your head in a box and a camera and screen showed the sunblock as black paint.

If an IR type of material could be made you could paint geometric dazzle type paint on your face to obscure its geometry.

2 - eyes and the facial geometry around them are secondary, so no nose and giant movie star sunglasses adds to the machines confusion

3 - collar worn sparkle lighting directed upwards is baffling to machine - silly things keep picking up the light sparkles on the face as feature points (heh)

4 - makeup patterns based on the WW2 ship camouflage mess up geometry detection

Now, all of that will defeat a simple recognizer but if the developers had a lick of sense, the system will still pop it out as anomalous.

Mission impossible facial masks could certainly help, but pretty much everyone is removing the IR filters at this point and the facial thermography would be all messed up

Then there's all the work going on in recognizing more than just a face - I've seen some stuff on incorporating more of the body into the recognition pattern (I've always wanted to watch one of those systems misrecognize Mitch McConnell as a turtle :-) As the available horsepower continues to expand, more of the totality of the individual can be recognized (my own accidental contribution to this is that cheap stereoscopic vision makes it a lot easier/more accurater to pick out foreground from background) At the end of the day, I think Scott McNeally had it right in the '90s - "You have no privacy. Get over it" I am of mixed minds about this stuff in public spaces, the good and bad examples are evenly distributed