I just tried "1020982208818642216" with PCMCv1.12.1 vanilla and did not get what you show.
Do you, by any chance, have any mods loaded?
Here's the map of the world I got when I tried this seed in Amidst and in vanilla Minecraft.
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There are no dangerous weapons. There are only dangerous people. R.A. Heinlein
If you aren't part of the solution, then you obviously weren't properly dissolved.