Can't buy Subscription

[The Bandito]

I tried to buy a month of a complete set subscription today, but twice instead of the payment page taking me back to dominion.games and showing me my purchased subscription (as is usual) it just went back to a blank payment page.  When I check on dominion.games, it still doesn't have a subscription, and my card was not charged.  I've tried twice now with the same result. Username on dominion.games is "The Bandito"

[Ingix]

Stef, the developer, checked this and both times the charge was declined during authorization. This has been reported several times over the years for a small number of people.

1) Is it a new credit card?
2) Did something change regarding the security mechanisms used by the card issuer?

It seems like American card issuers find it at least suspicious if suddenly a charge comes from a European place in €. They may want you to verify it in a way you are not even aware of. EU regulations also pushed for 2-factor authentication with credit card online usage, which was rolled out over the last years.

It's of course not helping that Mollie (the payment provider used) isn't actually saying that the card was declined.
 
Potential solutions are using another credit card if possible, another payment mechanism (which differs by country so I can't say much about that) or contacting your bank/card issuer about the charge and asking them how to authenicate 'unusual' charges.