Command Block Minecart drops a minecart named "@" if it is spawned using a spawn egg and broken in Creative Mode

This minecart renamed as "@" only drops if the command block minecart is spawned using a spawn egg and broken in Creative Mode. It does not drop if the command block minecart is spawned by a spawner, spawned with /summon, or broken in Survival Mode.

Use this command and try it out:
/give @p bee_spawn_egg{EntityTag:

{id:"minecraft:command_block_minecart"}

}