Grass and mycelium can spread to dirt blocks which are submerged under hacked water

The bug

Grass and mycelium can spread to dirt blocks which are submerged under hacked water.

Steps to reproduce:

1. /fill ~ ~1 ~ ~13 ~1 ~13 water
2. /fill ~ ~ ~ ~13 ~ ~13 blue_coral_plant
3. /fill ~ ~-1 ~ ~13 ~-1 ~13 dirt
4. /gamerule randomTickSpeed 1000
5. Make sure it's day (/time set 0)
6. /setblock ~ ~-1 ~ grass_block
7. Watch