In Fall; or, Dodge in Hell by Neal Stephenson one of the characters happens by a group of young women wearing devices that project constantly changing colored light patterns onto their faces to prevent facial recognition tracking. It's barely even mentioned in the book but I wondered how viable that was of an idea. The character's only thought on the devices IIRC was that most people only occasionally wore them.

As with most things cyberpunk, Gibson also did this masterfully w/ the Panther Moderns, specifically Lupus Yonderboy. One of my favorite parts of Neuromancer is when Lupus has his interaction with Armitage and says (from the link below) "Lupus didn't bother to count it, being sure that 'Mr. Who' paid well to remain so, and not be a 'Mr. Name', which Armitage received as a threat."

Gibson (and later Stephenson) were prescient enough to realize that anonymity would be a commodity in the near future.

https://williamgibson.fandom.com/wiki/Lupus_Yonderboy

Really excited to see what Apple does with these guys in the upcoming adaptation.

It would work until algorithms were adjusted to it, which would happen as soon as significant number of people started doing it. Colors are defeated by desaturating, which is no issue since most face recognition algos run on greyscale data anyways. Blotches of bright and dark are defeated, for example, by a high-pass filter (eg: edge detection) on the brightness data to filter out large blotches but keep small detail