What are the chances of pulling all full-arts and shiny cards?

I'll post a picture of the pack in the comments for reference, to stay within the rules of the sub reddit, but I just started playing yesterday so I genuinely have no idea how the pull rates for this game works. I opened a pack and every single card was a full art or shiny. I had no idea this was even possible, I assumed the packs would be like physical card packs with only one rare card. Needless to say, I was quite flabbergasted and almost felt like it was some kind of bug. Are there specific chances to just open a pack and it be all full arts and shinies?