It was one of the old leather tubs that were gained by a bug that allowed you to use normal dyes on the tub to change the colour.
When the patch came in to revert all types of the bugged tubs, it was left with the last colour set, in this case, neon blue and will stay like that unless you try and change the colour...
Legal/not legal is up for debate (not on this forum though I think), and so let the buyer beware!