Biome blending doesn't work in worlds that used official prototype datapack

Biome blending doesn't work in worlds that used official prototype datapack

Expected results:
Biome blending would work

How to recreate this problem:
1. Download 1.18 prototype datapack from official site 
Caves & Cliffs Prototype Data Pack for Minecraft Java Edition – Minecraft Feedback
2. Create new world in 1.17.1 with datapack
3. Explore world little bit so chunks would be generated
4. Exit world and open 1.18rc3 and ignore all errors load in "safe mode"
5. Find new chunks 
and you should see chunk glitches