The bug
The Cherry Grove biome does not appear in the 'buffet world customization' screen when creating a World Type: Single Biome. This is not consistent with every other Minecraft biome and unless explicitly noted otherwise, would appear to be a bug or oversight.
To reproduce
Open Minecraft, then click 'Singleplayer' -> 'Create New World' -> 'World'
Change the World Type: to Single Biome
Click on the 'Customize' button that is no longer greyed out
Note the absence of the 'Cherry Grove' biome in the list, despite all other biomes being present. Were Cherry Grove added as per other biomes, one would expect to find it between 'Birch Forest' and 'Cold Ocean'
goshdang it, despite reminding everyone else of this week in week out, I didn't enable the 1.20 pack first 😞 can someone please close?