If the block entity ID of a spawner's block_entity_data is not equal to mob_spawner, then its tooltip still displays whichever mob is specified in SpawnData even though the spawner will be empty when placed.

How to reproduce

1. Ensure you are in Creative mode
2. Obtain a spawner using this command:

   /give @s spawner[block_entity_data={id:ZZZ,SpawnData:{entity:{id:zombie}}}]

3. Inspect the item tooltip
   → The tooltip says "Zombie"
4. Place the spawner
   → The spawner is empty

Expected result

The item should have the default monster spawner tooltip.