The bug
Bonemealing a waterlogged big dripleaf stem creates a waterlogged big dripleaf stem above it, regardless of whether it is underwater or not.
A video is attached.
How to reproduce
Place a big dripleaf in shallow water (1-block deep)
Right-click the stem with bone meal a few times
→ ❌ Notice the new stems above the water generate as waterlogged above the water surface
Linked issues
is duplicated by 6
1 more links
Can confirm.