LTW3/data/minecraft/loot_tables/blocks/light_gray_banner.json

{
  "type": "minecraft:block",
  "pools": [
    {
      "rolls": 1.0,
      "bonus_rolls": 0.0,
      "entries": [
        {
          "type": "minecraft:item",
          "functions": [
            {
              "function": "minecraft:copy_name",
              "source": "block_entity"
            },
            {
              "function": "minecraft:copy_nbt",
              "source": "block_entity",
              "ops": [
                {
                  "source": "Patterns",
                  "target": "BlockEntityTag.Patterns",
                  "op": "replace"
                }
              ]
            }
          ],
          "name": "minecraft:light_gray_banner"
        }
      ],
      "conditions": [
        {
          "condition": "minecraft:survives_explosion"
        }
      ]
    }
  ]
}