The Bug
If you jump or fly around the worldborder, you will notice the border follows you but only for the y axis.
Reproduce:
1. Run /tp @s 29999980 ~ 0
2. Fly up and down
Note:
Using this bug, you can put the worldborder above and below the height limit.
Linked issues
Attachments
Comments 2
Thank you for your report!
We're tracking this issue in MC-206805, so this ticket is being resolved and linked as a duplicate.
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The world border not rendering above the height limit was actually a bug! That has been fixed in a recent snapshot, which caused the behaviour you're seeing. This has actually already been reported and is being tracked in MC-206805.