Decoration blocks added to Vanilla caves, they don't have special items as uses just yet but will have functionalities, such as brewing maybe.
Datapacks can be used to tune up/down the count of specific placements, or more detailed/specific modifications.
A default datapack can be downloaded here containing all the original files. (Or if you don't trust it, you can download them from the open sourced repository)
As an example, count can be modified in xxxpack/data/caveblooms/worldgen/placed_feature/xx.json
And other details like shapes and spread can be modified in xxxpack/data/caveblooms/worldgen/configured_feature/xx.json
