The Bug:

Spawners and trial spawners have the wrong color on maps.

Steps to Reproduce:

1. Summon some spawners and trial spawners beside you by using the commands provided below.

   /fill ~1 ~ ~1 ~9 ~ ~9 minecraft:spawner

   /fill ~-1 ~ ~-1 ~-9 ~ ~-9 minecraft:trial_spawner

2. Obtain a map, use it, and look at the color of the spawners and trial spawners on the map.
3. Compare the color of the spawners and trial spawners on the map to the texture and color of spawners and trial spawners.

Observed Behavior:

The map color of spawners is gray but their textures are dark shades of blue and the map color of trial spawners is gray but their textures are light shades of blue.

Expected Behavior:

The map color of spawners would be a dark shade of blue and the map color of trial spawners would be a light shade of blue.

Code Analysis:

Code analysis by Avoma can be found below.

The following is based on a decompiled version of Minecraft 23w51b using Mojang mappings.

public class Blocks {
   ...
   public static final Block SPAWNER = Blocks.register("spawner", (Block)new SpawnerBlock(BlockBehaviour.Properties.of().mapColor(MapColor.STONE).instrument(NoteBlockInstrument.BASEDRUM).requiresCorrectToolForDrops().strength(5.0f).sound(SoundType.METAL).noOcclusion()));
   ...
   public static final Block TRIAL_SPAWNER = Blocks.register("trial_spawner", (Block)new TrialSpawnerBlock(BlockBehaviour.Properties.of().mapColor(MapColor.STONE).instrument(NoteBlockInstrument.BASEDRUM).requiresCorrectToolForDrops().lightLevel(blockState -> blockState.getValue(TrialSpawnerBlock.STATE).lightLevel()).strength(50.0f).sound(SoundType.TRIAL_SPAWNER).isViewBlocking((arg_0, arg_1, arg_2) -> Blocks.never(arg_0, arg_1, arg_2)).noOcclusion().requiredFeatures(FeatureFlags.UPDATE_1_21)));
   ... 

If we look at the above class, we can see that spawners and trial spawners use the map color "STONE". This seems a bit strange since the textures of spawners are dark shades of blue and the textures of trial spawners are light shades of blue.