I was on the town base world when I found this out. It's very buggy and weird. You can only move with an Elytra and fire works. Most blocks are slab shaped.
I have attached some screenshots.
It may work in the newer bedrock version as well.
I will update the post when I find out.
The actual version I am using is 1.17.32 but I had to choose a available version so I picked 1.18.10.
Update. Now proven to work on the latest version of bedrock!
I also found more variations at different coordinates! And you can fall down through bedrock when your not flying.