The photo looks a lot worse than mine. If you can return it for one that looks better, you should. As I said, mine is faint and not in the actual text of the book, so it does not bother me.
The firmware you listed might indicate that the Aura's available in Portugal are from the first batch since this is from the time of the Aura release. See this link -
https://www.mobileread.com/forums/sho...d.php?t=185660
I would expect the firmware to update to the latest version as soon as you sync with Kobo for the first time.
Good Luck!