The Bug:

Sand and gravel within ocean ruins often convert into falling blocks when the world generates, resulting in performance drops.

Steps to Reproduce:

1. Generate and load into a completely new world.
2. Summon a repeating command block that will constantly alter the NBT data of any nearby falling blocks to make them glow and have no gravity by using the command provided below.

   /setblock ~ ~ ~ minecraft:repeating_command_block{auto:1b,Command:"execute as @e[type=minecraft:falling_block,nbt=!{NoGravity:1b}] run data merge entity @s {NoGravity:1b,Glowing:1b}"}

3. Locate an ocean ruin and teleport to its location by using the command provided below.

   /locate structure minecraft:ocean_ruin_cold

4. Allow the chunks around you to load.
5. Look for glowing falling block entities around the ocean ruin.
6. and take note as to whether or not sand and gravel within ocean ruins often convert into falling blocks when the world generates, resulting in performance drops.

Observed Behavior:

Loaded structures briefly create falling block entities.

Expected Behavior:

Blocks are placed directly and don't fall.