Ink seeps into farmbox?

Hello. Recently i have been growing vegetables in small planting boxes in a garden, and just a month ago i transplanted some cucumber sapling sinto the soil and stuck the coloured paper packaging (well it was sort of a paper-plastic material) in the soil to mark it as the cucumber pot. After about two weeks in which I did not visit the garden, when there was a lot of rain, I revisited and found that the packaging had loss its colour, and I am concerned whether this would lead to heavy metal pollution in the soil!

The packaging was white with a photo of two green cucumbers and a greenish background. After two weeks (today), when I returned, I found that all the coloured portions of the packaging turned light blue, and the rest remained white. I am worried whether the ink has been dissolved in rainwater and seeped into the soil, leading to possibilty of heavy metals on it (because there shouldn t be).

It is difficult to google relevant information, but I did manage to find an article about the UV radiation from sun decolourising objects.

Can anyone help me determine the possible truth of this situation? :( thanks