Summary
When you bonemeal the moss block on the tuff, it doesn't spread to grow lush plants. This isn't in parity with Java Edition, where you can bone meal moss block on tuff to get lush plants.

Step to Reproduce
1. Place down a few tuff block.
2. Place a moss block inside the tuff block.
3. Bone meal on the moss block to get lush plants.
---> It doesn't spread and replace the tuff block, instead, it only bone mealed the original moss block.