This bug applies to most "baby" mob variants. When a baby mob tries to jump and there is an opaque block above it's head, OR if the mob is forced to hug the ceiling with a Soul Sand bubble column, it will begin taking suffocation damage. I have tested only Baby Cows and Baby Zombies, but their results are identical. It might be due to a incorrectly sized hitbox on the smaller mobs that is inaccurate to their collision.

The video presents a comparison between an adult Zombie and a baby Zombie in identical bubble columns, being pressed against an opaque ceiling. Only the baby Zombie is taking suffocation damage.

This is a troubling bug, as farms that use bubble elevators to funnel baby mobs, such as animal breeders, will suffocate some of the offspring.