I am really not sure. I suspect that the
colorColor blindness
Color blindness tests
Color vision test is something touching your lips from the outside, rather than something from within. I advise you to catalogue any chemicals, colorants, dyes in oral products like toothpaste, or anything that could be coming in contact with your lips. I then advise you to see a skin doctor and to bring any photographs which might document the extent of the change you believe you are seeing.
Best.
Dr. Rockoff