New Unobtainable Foil?

I logged on and immediately started a duel with a standard duelist. I was a dingus and forgot to hit the save replay button so I have to go by memory. It was a duelist playing the Angel and Mythical Beast Deck, but instead of playing the correct cards, the CPU opened with a Ryu-Kishin with a strange foil. The foil had a rainbow like shine and sparkled. The computer did a tribute summon of a card (I don’t remember which) and it had the same foil! Beating the CPU did not give any of the cards. I tried searching it up and found no results. Did anything similar happen to anyone else and is there a way to get this foil on my cards?