Eli google is very slow but hey at least it doesn't use AI. I checked the citations of the 2016 paper and it's still being cited to this day. So based on a 2023 paper, this is one of many explanations. They're still not even sure they can see colors as their behavior suggests they can't as well as their one photopigment, but their camouflage suggests they can. The other explanations (all presented as equally accepted and likely) are reflective iridophores and photopigments + light provoked responses on their skin. They said their vision and the neuroscience around it is really under researched and I think the bigger thing to prove is that they see color at all which is why you're not finding much on how they see color.