Steps to Reproduce
Summon a baby villager in a chamber with the only escape being under half slabs

Expected Results
Baby stays inside chamber, maybe tries to jump against the walls a bit

Observed Results
Baby runs right under half slabs

Other Information

• This only seems to happen with some baby villagers – it took me a few tries to get one that would do this. This is most noticeable in villager breeders and open trading halls.
• It does not need to be double slabs as shown in the video.
• When running from a mob (ex: zombie), they don't seem to try to escape through the slabs. Cannot push them under either. Seems it must be of their own volition.
• Unsure if this happens with baby zombies.
• Attached world download logs in facing a baby villager surrounded by slabs. That villager should be able to run out from under the slabs if it decides to do so.