What I expected to happen was...:
Nothing out of the ordinary. Villagers in trading hall would all still be there.

What actually happened was...:
Every villager in my trading hall disappeared completely so I had to revert back to 20w06a

Steps to Reproduce:
1. Make a game in 20w06a and spawn some villagers, pair them to a bed and a workstation and trade with them
2. Relaunch game in version 20w07a
3. All the villagers will be gone, at least that's how it was in my case.