Well roads overlapping features is fixed but overlapping pieces of the same structure is still a issue.
Still in 1.21.120
Fixed in 1.21.122 it seems
Lilybeacon said up there about taiga_lamp_post_1.nbt, plains_accessory_1.nbt, and plains_fletcher_house_1.nbt that they couldn’t find the cause for them not generating. I suspect that the template pool needed to generate them simply doesn’t have them as a selectable element or the element is broken and can be picked or the jigsaw block within the file is broken and does not have the proper settings. Its not referencing the file because it isn’t being told to I suspect.
The stone and grass blocks generate because that's where the structure data mode blocks were that generate the mobs, they seem to replace them selves with the block that was there before the structure generated instead of air like they are supposed to.
Snowy Shepherds houses are also affected by this bug. Attachment_type of the Jigsaw block has a typo.