[r3trohack3r]

I think it goes something like this:

If your worried about anything in a 40 day window the credit card <-> account_id is a liability

Amazon doesn’t know the redemption code on the gift card. So Amazon knows that you purchased a Mullvad gift card, but can’t associate the transaction with a Mullvad account. Likewise Mullvad knows service was paid for with a gift card (possibly that the gift card is from a lot sold on Amazon). But they do not know which Amazon transaction the card is associated with.

Unless your behavior and the behavior of others deanonymizes the Amazon purchase <-> redemption your account should be indistinguishable from any other that purchased a Mullvad gift card from Amazon in that window of time.