Not sure if this is really a bug or not, but entities such as elder guardians in ocean monuments render before the chunks containing the structure render, causing the structure to be revealed.
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Avoma
Please could you provide some steps on how to go about reproducing this issue? Additionally, attaching some screenshots or videos showing this would be quite useful and greatly appreciated. Thanks 🙂
ampolive
This should be forward-resolved to MC-242331.
Brevort
This is actually because entities load faster than chunks, which cannot be fixed in any way.