The Bug:

Ocean monuments sometimes do not finish generating when upgrading a world from an older version with a partially generated ocean monument.

Reproduction Steps:

• Create a creative world with the seed "6381661193291299953" in 1.17.1
• Set your render distance to 2 chunks
• Execute the following command

/execute in minecraft:overworld run tp @s -272.86 65.04 126.43 6.40 44.94

• Exit the world and load an affected version
• Turn up your render distance and fly to the other side of the ocean monument
  → Notice how the ocean monument is cut off