Okay I thought that this was just with the swamp hut but after flying in just one direction I found "sunken" boats, "underwater monuments", villages without any buildings, igloos, and even a desert temple. Do know that I only enabled villages and decorations, no other structures. Yet it put some in the preset itself. Here's the seed and preset:[7866685539846275499] [minecraft:bedrock,59*minecraft:stone,3*minecraft:dirt,minecraft:grass_block;minecraft:plains;pillager_outpost,village,biome_1,decoration,stronghold,mineshaft,lake,lava_lake,dungeon,ruined_portal]

EDIT: If I try to locate a sunken boat, it says that the structure does not exist/cant find it even though I am standing right by one.