The bug

While trying to reproduce a bug for another bug report I haven't made yet I have discovered a weird occurrence. Every time I generate this world with the same settings it looks slightly different.

Edit: This doesn't only affect this world, this affects every world and it also affects every chunk of every world.
Basically the lush caves decorator isn't seed related resulting in you getting different world every time.

How to reproduce

Create a singlebiome lush caves world with seed -8508883206669806165
Go to: /execute in minecraft:overworld run tp @s -26.34 -36.86 171.23 -482.09 41.75
The area looks like this:

Now exit to menu and recreate the world without changing any settings
The area now looks like this:

Repeat the step from Step 1 (create a new world with lush caves single biome and the same seed)

The area now looks like this:

Now recreate this world
This time the area looks like this:

As you can see each time this area looks very different.

It's so inconsistent I cannot predict if you will be able to reproduce exactly the same worlds I did

Basically only the shape of the cave stays the same and the decoration generation is entirely different each time.