When a non-experimental world is loaded with a spawner minecart containing disabled mobs, the spawner minecart will not be removed from the world.
Reproduce:
Download the structure file.
Place the file in the non-experimental world folder.
Loading minecraft:spawner_minecart to the world using structure blocks.
Use the following command:
/data get entity @e[type=minecraft:spawner_minecart,limit=1,distance=..3]
Notice that the disabled mob IDs(SpawnData:{entity:{id:"minecraft:camel"}}) in the spawner minecart are not cleared.
Or
Download the world file.
Use the following command:
/data get entity @e[type=minecraft:spawner_minecart,limit=1,distance=..3]
Notice that the disabled mob IDs(SpawnData:{entity:{id:"minecraft:camel"}}) in the spawner minecart are not cleared.
It also causes the game to output spam.
Game output
22:47:34.081
bdv
Server thread
Skipping Entity with id minecraft:camel
22:47:50.631
bdv
Server thread
Skipping Entity with id minecraft:camel
Confirmed.