Trees can be cut off at new chunk boundries when upgrading a world to caves and cliffs world generation

The Bug

Just before 21w43a came out, the snapshot where terrain blending is added, I posted a feedback about 21w42a that mojang has already applied chunk blending for 1.17 worlds on trees, corals, and structures. The next day, I checked the newest snapshot. I recovered my 1.17 world and opened it in the snapshot to see how the chunk blending is applied, and discovered trees are split in half again. It mainly happens when the 1.17 biome is dark forest. I can confirm this bug for 21w44a and 1.18 Pre-release 1. On the bottom left of the photo you can see the version of the world.

Reproduce

• Create a world in 1.17.1 or lower
• Go to a biome with trees
• Close and open the world in 1.18 pre-release 1 or higher
• Go towards the new chunks

Observed Result

The trees were cut in half

Expected Result

The trees would not get cut in half