I have tried searching here but got no matching results, so I believe it's a new bug.
When an End Gateway generates on the outer islands (by traveling through one on the main island) and happens to generate through chunk borders, the gateway is generated incompletely - only parts inside the chunk where the gateway block is at generates.
Steps to Reproduce:
Use this seed to create a world:
-261618638
Go to the end and kill the dragon (can be done by
/kill @e[type=ender_dragon]
)A gateway should generate on/near the -Z axis
Go through the gateway
Observed Results:
The gateway on the outer islands is sometimes cut by chunk borders and thus incomplete.
Note: The exact position that the outer-island gateway generates may vary slightly so it's not cut by chunk borders every time; if this happens, delete the world and re-create one using the same seed, until you see the incomplete gateway. Also the result may be inconsistent: while the gateway gets cut by the chunk border, sometimes it is completely generated but sometimes not; some part beyond chunk boundary (in this case, corner of the chunk) will be missing randomly.
Expected Results:
The gateway should be generated completely regardless of whether it is cut through by chunk borders.
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However, this issue has been temporarily closed as Awaiting Response
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Tested on 1.17.10 and found the bug still there, and was inconsistent: while the gateway gets cut by the chunk border, sometimes it is completely generated but sometimes not; some part beyond chunk boundary (in this case, corner of the chunk so this gateway is next to two chunk borders) will be missing randomly.
I have updated the descriptions to comply with the given example style.

Affects 1.18.2.
In my survival world, I built a platform around the gateway at the main island and then threw an ender pearl into it. The first time I was teleported back almost instantaneously and began suffocating in the bedrock, but jumped out and emerged on top of the gateway. I tried again and was teleported to the outer end islands as expected, but the gateway was incomplete. Not sure if the first issue caused the second due to chunks being rapidly generated and then unloaded, or if they're completely separate issues.
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