The Bug:
Ocean ruins and ravines can generate on top of kelp causing it to get destroyed and float to the surface. This can result in massive amounts of kelp item entities being created and thus causing lag.
Here are some examples:
Version: 24w34a
Seed: -895953179
Coordinates: /execute in minecraft:overworld run tp @s 43328.36 63.86 -468.24 -5282.86 33.71
Steps to Reproduce:
Generate a world with any seed provided above and teleport to the given coordinates.
Observe your surroundings and look closely at the nearby kelp.
Take note as to whether or not ocean ruins and ravines can generate on top of kelp causing it to get destroyed and float to the surface.
Observed Behavior:
Kelp is destroyed and floats to the surface of the water.
Expected Behavior:
No kelp would be destroyed.
Linked issues
is duplicated by 5
Attachments
Comments
Hemps get generated on top of gravel sometimes, and gravel sometimes is on top of water ravines. When gravel gets updated hemps get destroyed. Jokes aside but this being serious lag source for server owners. In some servers it is taking as a major part of item lag if world contains alot of ocean. 300-75 entities at each such location. 1-2 entities on places where this didnt happen for comparison.
I can't reproduce in 20w16a. Maybe fixed?
edit: apparently not
Well, I still can't reproduce it myself.
Can confirm in 1.16.4.

@unknown what seed and coordinates did you use to reproduce this in 1.16.4? I'm not able to reproduce in 1.16.4 at least with the seed and coordinates that have been mentioned previously in this ticket.
@unknown, sorry for the late response. Here is the seed along with the coordinates, where you can experience this issue. Also, can confirm in 21w05b. I'm not notified when a user responds to my comments, so if you wish to contact me directly, please do so via the Mojira Discord.
Seed: 4384550191293543872
Coordinates: /execute in minecraft:overworld run tp @s 432.96 64.47 3250.69 -122.78 28.54
There's a chance that in 20w07a the bug might actually be caused by underwater caves, which would be a different issue. But I updated the report to 20w07a.

Can confirm in 21w15a
Can confirm in 1.17.1.
Can confirm this in 21w40a.
[media]Seed: 326795066205547
Coordinates: /execute in minecraft:overworld run tp @s 28312.59 64.82 6.99 500.66 32.11

Can confirm in 21w43a.
Can confirm in 1.18.1.
[media]Version: 1.18.1
Seed: 3474760402194180070
Coordinates: /execute in minecraft:overworld run tp @s 101.51 68.15 2320.94 146.46 58.44
Can confirm in 1.19.
Version: 1.19
Seed: 3032665062407875672
Coordinates: /execute in minecraft:overworld run tp @s -152628.38 65.70 -5743.14 292.46 56.12
Can confirm in 1.19.2.
Version: 1.19.2
Seed: -2055074493936140863
Coordinates: /execute in minecraft:overworld run tp @s -10878.75 67.48 -253.71 -134.44 45.82

Affects 1.21

Confirmed in 1.21.3

Confirmed in 1.21.4 prerelease 2
Confirmed for 1.13.2-pre2.