When saving a structure with a structure block, the file is saved as <WORLD>/generated/<namespace>/structures/<id>.nbt, this is inconsistent with data packs, which need the folder to be singular: <WORLD>/datapacks/<PACK>/data/<namespace>/structure/<id>.nbt.
This is an inconvenience for data pack authors as they cannot drag-and drop the folder into their data pack, unlike before the data pack folder was renamed.