Summary:
In 1.18.0.21 Beta, using bone meal on crimson or warped nylium spreads nether sprouts, roots, and fungi to nearby dirt-like blocks. This is not supposed to happen according to MCPE-73775.

List of blocks:

• Grass block
• Podzol
• Mycelium
• Coarse dirt
• Dirt
• Rooted dirt
• Farmland

Steps to Reproduce:

1. Place crimson or warped nylium next to the blocks from the list above
2. Use bone meal on the nylium

Observed Results:
Nether sprouts, roots, and fungi spread can spread to the blocks from the list above.

Expected Results:
Nether sprouts, roots, and fungi should not spread to the blocks from the list above.

Video:
Minecraft 2021-10-14 14-13-55.mp4