eldirector
Grandmaster
Not just color copiers. A great many modern printers and copiers do the same. Even on black and white printouts.Exactly!
Interesting fact about the microstamp on color copiers.
https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots
https://en.wikipedia.org/wiki/Printer_steganography
https://w2.eff.org/Privacy/printers/docucolor/
So, if you register your printer with the manufacturer for the warranty, they can easily tie printed output back to you.