Just making a more official post here since this topic made a lot of confusion.
As it was stated in last year's topic, New Year Cards were no longer redeemable since this Christmas event started.
Past year's service was Shield and Armors upgrade, the post wrongly linked to Mags change topic because copy/paste from last year's post, as you could guess with the given dates.
Mags change service was a thing 2 years ago and may or may not return.
You will be able to redeem New Year Cards later, after Christmas event ends. There will be an official announcement about it when the time comes, and no one knows yet what they will do.