Summary:

This bug is not a duplicate of MCPE-140660 because the player does not create phantom blocks in this report.
Also this error is a consequence MCPE-59523.

The player can create flying (non-phantom) flowers.

Steps to reproduce:

1. Place a flower on grass.
2. Place a snow layer in the same space as the flower.
3. Place any non-full block (e.g. a slab), replacing the snow layer (the block should not drop when removing the support block).
4. Break the grass under the flower with the block.

Observed results:

The block was dropped, and the flower was left flying in the air.

Expected results:

The player must not create flying flowers.

Video:

Minecraft 2021-09-05 11-44-06.mp4