Oracle Cloud: Sign up failed “Error processing transaction”

I have already configured many accounts to use Oracle Cloud. Especially, since December 2020 I started to face some problems on the step where you must provide a credit card to simulate a payment but in fact, it works like a personal identification. So I have used the same card that I used previously in some setups, two other new cards and even asked some friends in different countries using their own cards and some of them have experienced the same erros while others could create their account successfully. Follow…