After the world is upgraded, BlockEntityTag's LootTable is converted to container_loot

After the world is upgraded to a new version, BlockEntityTag's LootTable is converted to container_loot

How to reproduce:
1. Use the pick block to get an item with loot (chest or suspicious sand) in 1.20.4
2.Upgrade to the new version
3. Use the /data command to obtain the data of the item

Expected behavior:
LootTable under BlockEntityTag should be converted to LootTable under block_entity_data component

What actually happened:
LootTable under BlockEntityTag is converted to
container_loot

Note: Upgraded Suspicious Sand (including gravel) cannot generate loot.(Please see MC-271530)