Affects Version/s: Minecraft 18w06a, Minecraft 18w07b, Minecraft 18w07c, Minecraft 18w10c, Minecraft 18w10d, Minecraft 18w16a, Minecraft 18w20b, Minecraft 18w20c, Minecraft 1.13-pre1, Minecraft 1.13-pre2, Minecraft 1.13-pre3, Minecraft 1.13-pre4, Minecraft 1.13-pre5, Minecraft 1.13-pre6, Minecraft 1.13-pre8, Minecraft 1.13-pre9, Minecraft 1.13, Minecraft 18w30b, Minecraft 18w33a, Minecraft 1.13.1-pre1, Minecraft 1.13.1-pre2, Minecraft 1.13.1, Minecraft 1.14 Pre-Release 5, Minecraft 1.14, Minecraft 1.14.2, Minecraft 1.14.3 Pre-Release 2, Minecraft 1.14.3, Minecraft 1.14.4 Pre-Release 1, Minecraft 1.14.4 Pre-Release 2, 1.14.4, 19w35a, 19w37a, 1.15 Pre-release 3, 1.15.1, 1.15.2, 20w09a, 1.16 Pre-release 2, 1.16.1, 1.16.2, 1.16.3
Fix Version/s: Minecraft 1.13-pre10
Some biome decorations such as
snow, trees and structures sometimes fail to generate, producing very distinct 8 × 8 sections of land within a chunk from the surroundings.
Mod edit: Fixed for all but trees as of 1.13-pre10
Something to note is that they appear to be random; after re-creating the world with the same seed and settings, some of these odd chunks are generated correctly, and other chunks which generated correctly before seem to suffer from this bug.
Duplicate photos from the attachments show two versions of the occurrence: two in different worlds with the same seed, but only one showing the glitch.
Because of the hard-to-reproduce nature of this bug, I can't guarantee the same seeds will produce the bug at specific places every time, but it should be easy to find an occurrence on a large ice plains' sheet of snow or villages' houses and paths.
If it's of any help, here's the seed of the world I took the screenshots on: