Some entities are not rendered as bright as they should be when used as the 'displayEntity' (or rather, the 'summoned mob') of a spawner.

Steps to Reproduce:

1. Place down a monster spawner, or trial spawner
2. Use a blaze spawner on it
3. Tick freeze for easy observation

   /tick freeze

Observed & Expected Results:

- The blaze is rendered very dim compared to when the blaze is spawned as an entity.
- The blaze would be rendered exactly how it is rendered in entity form.

Screenshots/Videos:

Notes:

1. This also affects all entities that are burning:

   /give @p spawner{BlockEntityTag:{SpawnData:{entity:{id:"minecraft:zombie",Fire:1000,HasVisualFire:1b}}}} 1
   

2. Currently affected entities are:
   

Code Analysis:

The entities listed are affected because they override the `getBlockLightLevel()` method inside `net.minecraft.world.entity.Entity` by always returning 15 (the brightest block light level) instead of using a shader to render brighter like done with the emissive 'eye' layers of entities such as spiders, endermen, or phantoms (which all behave normally inside spawners).

The regular behavior for entities:

net.minecraft.world.entity.Entity

   protected int getBlockLightLevel(T entityType, BlockPos blockPos) {
      return entityType.isOnFire() ? 15 : entityType.level().getBrightness(LightLayer.BLOCK, blockPos);
   }

(As an example) The behavior for blazes:

net.minecraft.client.renderer.entity.BlazeRenderer

   protected int getBlockLightLevel(Blaze entityType, BlockPos blockPos) {
      return 15;
   }