On a Bedrock world, we have an automatic chicken killer. Eventually however, we discovered the area around the cooker was extremely laggy; chickens were escaping.

Apparently, baby chickens can rocket through multiple blocks when dispensed onto a half slab, clipping though one or more blocks.

Steps to reproduce

1. Make a 1x1 enclosure with a half slab on the bottom.
2. Spawn/Dispense a fair amount of mobs inside the enclosure. In the videos I placed 30 regular chickens (it only happens if there are mobs already in the enclosure)
3. Dispense additional baby chickens into the enclosure.
4. Watch as the new baby chickens rocket out.

In the screenshots/videos, I created two nearly identical enclosures, but one of them has a half slab on the bottom, and one does not. I placed 30 regular chickens inside each using the summon command, and dispensed baby chickens using eggs and a repeated. Only the half slab enclosure had issues.