This bug report is a parity issue with Java.

Summary:

In the Java version, when the player uses bone meal on a moss block, only adjacent stone blocks are replaced, and vegetation grows on them. In the bedrock version, moss carpets, grass, and azalea bushes grow on any blocks available nearby. Including the block itself on which the player uses bone meal. 

(If there is no stone nearby, nothing should grow. Not even the grass on the Grass Block)

As of version 1.16.230.52, vegetation appears only on a block of moss. There is still a problem of parity.

Steps to reproduce:

1. Place the moss block (where there is no stone nearby).
2. Place blocks other than stone at the same height as the moss block.
3. Use bone meal on the moss block.

1.16.230.52

1. Place moss blocks in a small area (where there is no stone nearby).
2. Use bone meal on the moss block.

Observed results:

Plants will spawn on the moss block.

Expected results:

Already placed moss blocks should not grow anything.

Video:

Bedrock (1.16.230.52) Minecraft 2021-04-01 19-37-24.mp4

Bedrock 2021-03-20 10-29-10.mp4

Java 2021-03-20 10-22-47.mp4

Java (2) Minecraft 21w13a .mp4