Australia red eyed tree frog skin colour question

[Frogs1]

Hi, I recently got some Australian red eye tree frogs. I noticed on 1 of them he had lots of these brown dots on his lower part of the back and lighter ones around the other parts of his body. Before I bought them they recently went from the white stage to the green one. I was wondering if this has anything to do with that or if it's something else. Thanks