Summary:
Gravity blocks don't fall when placed on replaceable blocks.
For example, if you need to put sand on the grass, for this you will need to place 2 blocks next to each other and place a block with gravity above the grass, aiming at one (upper) of the placed blocks. This is also described and fixed with the snow layer in MCPE-151407.
All blocks that can break when blocks with gravity fall on them are affected (except snow, starting from the version 1.18.30.21 Preview, 1.18.30.20 Beta).

Affected Blocks:

• grass
• tall grass
• fern
• large fern
• sea grass
• tall seagrass
• vine
• glow lichen
• warped roots
• crimson roots
• nether sprouts
• dead bush
• structure void

Steps to reproduce:

1. Place any block that can break when a gravity block falls on it or that can be replaced with another block (eg Dead Bush).
2. Place 2 blocks side by side (if you used for example Tall Grass place 3 blocks).
3. Aiming on the topmost placed block, place above the replaceable block, the block that has gravity.

Observed results:
The block did not fall.

Expected results:
The block should fall and break the block underneath it (as in the java version and as with the snow layer from version 1.18.30.21/1.18.30.20).

Video:
Java Minecraft 1.18.2 - 2022-03-07 23-05-56.mp4
Bedrock Minecraft Preview 2022-03-07 23-04-54.mp4