this title is kind of a lie as pink eyes are still very rare and can only occur in one very specific breed with a very rare mutation, they have to be from a relatively small lineage and they aren't fully pink but pink and yellow but bear with me. a few sources used (lost some): http://messybeast.com/dilution-factors.htm#:~:text=PINK%20EYED%20DILUTION%20Pink-eyed%20dilution%20is%20found%20in,red%2Fpink%20irides%20%28the%20coloured%20section%20around%20the%20pupil%29. https://donskoydiscovery.blogspot.com/p/unverified-color-mutation-in-donskoy.html
No, the cats in the project aren't the result of the camera flash. In the breed known as the 'Ukranian Donskoy' a special genetic mutation causes cats to have a red/pink iris with otherwise yellow eyes. Not a lot is known about it yet and it only appears every few generations. It usually gets ignored in roleplays as not a lot is available to research but from what I've found it doesn't affect anything other than the eye colour. If your cat is a kittypet or formerly a kittypet it isn't too ridiculous for them to be a Donskoy cat with this mutation. Usually cats with the Pink Eye Dilution are dusty brown but can be sort-of pinkish as shown in some photos I've included.