I have a new 1.17.11 world running on official Mojang server software. I have defeated the dragon several times and started a build involving the main end island. At 4 random locations now, small end islands, like those that spawn far out in the end, are spawning close to the surface of the main island. They spawn and it deletes blocks that have been placed. The attachment shows the 4th island that has spawned.
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