Falling blocks with NBT data do not transfer NBT data to item when they are destroyed

Run the following command:

/summon minecraft:falling_block ~ ~ ~ {BlockState:{Name:"minecraft:white_banner"},TileEntityData:{Patterns:[]},Time:1}

If you run this command above a solid block, the falling block will place a white banner with a black creeper face. However, if you run this command above a slab, which will cause the falling block to drop as an item, the NBT data is lost and you will be left with just a white banner without patterns.