Chunk border is very straight when the 1.18 terrain has a mountain, and the older terrain a sea

As the title sais
Steps to reproduce:
 - Make some worlds in 1.17 and load all chunks within a a specific render distance (don't move)
 - Update to the newest prerelease and find the border
 - Go along the border and you will sometimes find this

• World Type: "Default"

• No additional generation settings

• Seed: 9184991237633477144

• Coordinates: 118.05 135.51 -293.96

• Render distance used: 16

• World download: https://drive.google.com/file/d/1zcHNn11jWrN8UzUpUWHfEiAXWnoPVl07/view?usp=sharing