Okay so this happened twice. I was just going to the nearby bastion not that far from my nether portal and as I pass by some Piglins, a baby Piglin will occasionally die when in one block tall spaces (tall enough for the player to crawl as of 1.14.) I said this happened twice, but only one of those times was a Chicken jockey, the other time it was the baby Piglin on it's own under a stair I made to get down to a lower ledge. I think this is just strange and it could be a bug.