When you update your custom map to 1.20.5, custom spawn eggs break due to incorrectly converted custom entity ID.

Note: In 24w09a exclusively, the EntityTag NBT tag is properly being converted to the minecraft:entity_data component, with the id being retained.

To reproduce

• Launch Minecraft 1.20.4
• Create a world
• Execute

  /give @s minecraft:enderman_spawn_egg{EntityTag:{id:"minecraft:cow",Tags:["i'm-a-cow"]}}
  

• Check the item data or try to spawn an entity using it
  
• Leave the world
• Launch Minecraft 1.20.5 and open the world in it
• Check the item data or try to spawn an entity using it
• See the corrupted ID