Alright so, after buying something from the site my card was locked and now I have to confirm purchases to see if there's an fraud. The first one was the amount I spent on a game going to a hobby and game shop in Poland, which I assume is GOG, being Polish.
but the second was the same amount for a hobby and game shop...in California. What's up with that?
Most banks have security protection which may lock a card if they detect that the card is being used in a manner unusual for the card holder. That includes things like shopping habits changing all of a sudden compared to all previous usage of the card, repeated purchases in a short time window or any other "tell tale" signs which often accompany fraudulent card usage.
It is good to talk directly to your bank to learn about how their security measures work and what you can do proactively to ensure your online shopping (anywhere, not just on GOG) does not trigger their security protection mechanisms.
For example, GOG used to do payment processing in Cyprus, which would trigger a lot of banks to put cards on hold because a lot of fraudulent activity online happened through financial institutions in Cyprus at the time. So when a bank saw sudden transactions on a card going through Cyprus, with no previous purchases on the card going through there it triggered some security red flags, so they put a hold on the card until the customer can confirm for them that it was a legitimate purchase. In my case, my credit card company called me immediately on the phone after a purchase to confirm who I was and that the purchase was legitimate. After confirming it was a legitimate purchase, they put on my file that purchases from GOG were authorized so I wouldn't have problems in the future. I don't believe GOG still does processing through Cyprus anymore but I'm not certain, it could still be a thing.
Whenever someone is planning on potentially using their card for a purchase online which might be unusual compared to their past or recent card activity on a given card, it never hurts to call the credit card company up first and inform them of upcoming purchase plans so they can make a note on file. It can help to avoid security freezes on cards. All you have to do is call them and say "I'm planning on using my card on an online store I've never shopped at before and I want to inform you that the purchases will be legitimate so you can put it on my file." or something like that. Takes only a couple minutes usually and makes the whole process of online shopping anywhere much less likely to trigger security alerts.
Hope this helps.