This actually affects 20w18a, but who cares anyways.
Before 1.16 snapshots: Overworld superflat preset is normal; it has trees, lakes, mineshafts, villages, etc.
Now: Random structures appear all over the world, even when the biome isn't correct. With the normal overworld preset, it's a plains biome. But you can find a desert temple, jungle temple, ocean ruin, shipwreck, witch hut, and even igloo. Even though u can see them, if you do /locate shipwreck for example, it says, "Cannot find structure within a reasonable distance", even if you can see it right in front of your eyes!!!
Thank you for your report!
We're actually already tracking this issue in MC-180603, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
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