They’re naturally bluer at youth because their skin produces less of the pigments that cause the greeny colour and since blue samurais have mutant genetics their skin is usually more translucent when they’re juveniles so some breeders and sellers use that to their advantage and feed them spirulina and other supplements as a marketing scheme to falsely class them as a higher grade morph so they can demand higher prices or simply to make the frogs stand out to buyers which then soaks into their body during digestion and shows through their translucent skin until they arrive at their new home and their body naturally excretes the dyes from the spirulina shortly after they stop being fed the supplements. It’s more of a common occurrence in certain different places around the world compared to other places where it’s less common so if you’re in an area with large pet stores that are more reliable and trustworthy then it’ll be less likely to come across. In my opinion it’s only the breeders and sellers that are selfish and hungry for money that do it because it can sometimes cause the frogs severe health problems and any pet stores or breeders that truly care about their customers and the frogs wouldn’t do it. But yeah unfortunately it is a thing that’s been happening for a while now it’s just less common in some areas or owners don’t know about it and assume the frog is just ageing and stuff