Despite the change log stating that Firefly Bushes generate in the swamps, they only generate in the classic Swamp biome and not the Mangrove variation. There are none throughout the biome, not even near bodies of water.

Steps to Reproduce:

1. Generate a new creative world (preferably using the seed 4000051, as it has many vast mangrove swamps next to spawn, but you can test it on any seed as many times as you'd like). Make sure to enable cheats when making the world.
2. Place 4 command blocks on the ground in your spawn chunk, and set them all to "Repeating" and "Always Active".
3. To help observe the ground clearly, put each of these commands into the four command blocks, respectively:

   /execute at @p run kill @e[type=minecraft:item]
   /execute at @p run fill ~-20 ~-10 ~-20 ~20 ~8 ~20 air replace minecraft:mangrove_log
   /execute at @p run fill ~-20 ~-10 ~-20 ~20 ~8 ~20 air replace minecraft:mangrove_roots
   /execute at @p run fill ~-20 ~-10 ~-20 ~20 ~8 ~20 air replace minecraft:mangrove_leaves
   

4. Use the following command to locate a Mangrove Swamp, and teleport to it:

   /locate biome minecraft:mangrove_swamp
   

5. Fly around and look for Firefly Bushes.

Expected Result:

You would find Firefly Bushes scattered around the biome as they are in the classic Swamp.

• This is consistent with the other Swamp variant.
• It is in parity with Bedrock Edition.

Observed Result:

You will not find Firefly Bushes, only occasionally spotting them on the edge of the biome if there's a swamp nearby.

• This is inconsistent with the other Swamp variant.
• It is not in parity with Bedrock Edition.