The Bug:

Cave vines can sometimes generate within the end portal frames.

Steps to Reproduce:

• Enter the following seed & coordinates.

Caves & Cliffs 1.17.1 Datapack Preview
World Type: Single Biome, Lush Caves
Seed: -1290361904797768774
Coordinates: /execute in minecraft:overworld run tp @s -8375.89 -5.00 1791.24 26.44 30.38

• →  Notice how cave vines can sometimes generate within the end portal frames.

Information:

This isn't a major issue because the cave vines get replaced when the end portal activates.

Expected Results:

Cave vines should not be able to generate within the end portal frames and this space should only contain air.