pumpkin-java-multiversion/assets/datapacks/26_3/data/minecraft/recipe/bamboo_mosaic.json

{
  "type": "minecraft:crafting_shaped",
  "key": {
    "#": "minecraft:bamboo_slab"
  },
  "pattern": [
    "#",
    "#"
  ],
  "result": {
    "id": "minecraft:bamboo_mosaic"
  }
}