The blend is incorrectly applied to the terrain

The chunk they spawn correctly the first time, but when exiting and re-entering the world, the chunks become unstable and the terrain breaks.Caused by poor application of blending.

Steps to reproduce

1. import World 1.16.221.mcworld and convert world to infinite
2. Enter the world and explore new chunks outside the limits of the old world
3. Leave the world and re-enter

Expected results:
The chunks are generated is stable and the terrain blending is good.

Observed results
The chunks become unstable and the ground breaks.