Random signature legendary showed up in my collection.

Yesterday morning when I woke up I spent my 2k gold I had saved up on some regular new packs. On like the 3rd pack I opened it bugged out and one card wouldn’t turn over, and it had no rarity color around the border. I couldn’t back out of the pack opening so I just force closed my game and reopened. Opened the rest of my packs, got two regular legendaries out of my 20 packs so I wasn’t complaining at all.

Building a deck and I see a recommendation for shaldrassil and I’m like wtf? Where did this come from? It had to of been that one card that wouldn’t turn over when my game bugged out.

Definitely a pleasant surprise lol. Has anyone else ever had this happen?