Well, instead of asuming, if you don't know what it says on the picture you can always ask.
It says "Double Gold Coins" in the Link's Awakening inage. The other text says: "Save up to 30,99 euros with the Nintendo Switch Vouchers".
I assumed 100% correct and the statement on the thing is still not untrue. It just so happens that if you buy the game with vouchers then you get no points to double because you've already gotten points for the purchase of the vouchers, they're not going to award points twice for the same single transaction of cash.
Fancy hearing me on an amateur podcast with friends gushing over one of my favourite games? https://youtu.be/1I7JfMMxhf8