Baby zombies, gurgles, baby husks, and baby zombie villagers can no longer traverse one-block-high passages

The new Baby Humanoid Mobs are now bigger than 16 pixels, which prevents them from entering 1 block wide holes.

Previously, they were smaller, and official Minecraft structures, along with countless fan made designs such as villager spawners and zombie traps, were designed with this in mind. They are now non-functional due to this.

For things to officially work again, the Baby Humanoid Mobs must have their hotboxes either equal or under 16 pixels.

Attachment is of a Trial Chamber Room that is left broken due to this error.