@Karandros:
what one must do to be able to buy them? DO I have to sell my soul to the devil first?
Don't sell your soul. The devil is having trouble getting SECs as well.
😉FYI, the Black Friday 2019 promotion provided a straightforward (though potentially expensive) path of getting these. Each time you spent credits on the slots or on a scratch card, you accrued points that eventually rewarded you with the Jia Lissa SEC card and, later, a Joker card. I don't know whether Totem will provide something similar in the future or not, but I would be surprised if they didn't. I'm keeping my Joker until there's an SEC I absolutely have to have.
@601bes:
suddenly I wasn't getting the prizes (creidts or cards) as much.
As you say, it's definitely subjective, but I feel the same way. I seemed to be a lot "luckier" when buying scratch cards during the Black Friday 2019 promotion than I have on scratch cards since then. Of course, that's how luck works, but it would be nice to know if the odds have actually changed..