Old description:
This was prevalent within the experimental snapshots as well, and has carried over to 21w37a.
Dead bushes will sometimes generate in biomes they aren't supposed to. You can see them in plains, meadows, taigas, savannas, etc.
Though generating in swamps is intended, they seem to do it much more often now.
The bug
With the introduction of 3D biomes, different surface biomes can now generate on top of one another, even when it serves no purpose. In the attached screenshot
[media], there is badlands above a plains biome. This can be confusing to players when they build with grass or leaves and notice different colors depending on the height.
This also leads to biome decorations being placed in wrong places. In the screenshot
[media], dead bushes from the above badlands biome are being placed down onto the plains biome.
Another side effect of this issue is special ore placement rules (such as abundant gold ore in badlands) break when a different surface biome generates below it (see MC-236705 - where a forest generated beneath the badlands).
Examples
[media]:
Seed: 1755992158
/execute in minecraft:overworld run tp @s 260.03 104.50 -1430.19 24.75 39.18
[media]:
Seed: 1755992158
/execute in minecraft:overworld run tp @s 308.59 116.65 -1564.51 -135.1 37.1
[media]:
Seed: 7591629109323498270
/execute in minecraft:overworld run tp @s 1225.98 100.41 -1265.78 -488.00 58.60
Linked issues
relates to
Attachments
Comments


Dead bushes are supposed to generate in swamps as per MC-169563.

Hm, well regardless there is still something happening with dead bushes elsewhere

Works as intended

Most likely it's due to a desert biome just spawning around, but can confirm

Robert Macedolian, source?

The generation of ground vegetation seems a bit off in general, probably due to 3D biomes.

Yeah, this is not only specific to dead bushes, even ferns are able to generate on forests now it seems (if there's a taiga/jungle at the top/bottom of the world).
Indeed due to 3D biomes.

It seems biome-exclusive mob spawning is also affected by this bug, hence this parrot in the birch forest. A few ways underneath the trees is a small jungle microbiome in the middle of the rocks. Should this be added to this bug or made into a separate report about mobs exclusively? I have another example of wolves spawning in a plains
[media]
(Moved from MC-236619)
Some other issues this could lead to:
Players might not necessarily need to go to "real" biomes to be able to progress in the "Adventuring Time" advancement.
/locatebiome command can teleport players to biomes that don't match the surface (floating biomes).
Inconsistent weather between heights (i.e. raining on deserts, snowing on forests) (MC-236652).
This happens due to the temperature and humidity variation between heights, therefore biomes with their corresponding parameters can get placed overlapping other surface biomes.

It also tends to mess up cave biome generation, making the floors of lush caves not lush and the like

Seems like it is WAI, but i don't think the misplaced vegetation is intended, so maybe it should be split into another report.

Thats honestly what this report was originally about, though I had only specified dead bushes

I've made the foliage issue a separate, specific report; MC-236894
Dead bushes could generate in swamps since beta 1.8, but they were really rare in the past because they could only generate on sand, which isn't very common in swamps. Since 1.17 they can generate and be placed on grass blocks, so they are more common in swamps now.