Chunk blending occasionally produces sharp chunk border edges

The Bug

Sometimes chunk blending creates rough edges, most commonly near water.

Reproduce

• Create a world in 1.11.2 with the following seed: 2858866457948012429
• Leave the game and load the same world in 21w43a
• Go here: /execute in minecraft:overworld run tp @s 264.64 74.15 93.81 -267.45 8.10

World Download

Download the world here and go to /execute in minecraft:overworld run tp @s 264.64 74.15 93.81 -267.45 8.10 to see the issue

Observed Result

A chunk border edge was created

Expected Result

No chunk borders would be made