Some flat world preset code: decoration or other code not working properly

Flat world preset code: decoration not working properly, there are no plantation or ponds generating in any form.

E.g.  'minecraft:bedrock,2*minecraft:dirt,minecraft:grass_block;minecraft:plains;village,decoration'

This code would generate a flat world with 'decoration' in 1.15, but in 1.16 pre-releases, it won't.

The presets that do not work in 1.16 and higher are :

• stronghold
• village
• biome_1
• decoration (tree & grass)
• lake
• lava_lake
• Probably other rules still