What I expected to happen was...:

To be able to use the /placefeature command in the experimental snapshot.

What actually happened was...:
It didn't show up as an option. All that showed up was /particle, /play sound, and /publish

Steps to Reproduce:
1. Start a Creative world in the 1.19 deep dark experimental snapshot.
2. Enter chat, and hit /p
3. See the only options available.