When you make a minecraft world on Java under Buffet: World Generation Caves: Giant Tree Taiga, the mossy stone outcrops break the bedrock above the world, along with water ponds. As you can see from the screenshot attached, the water ponds and mossy stone outcrops break through the bedrock, allowing players to get above the bedrock without enderpearls, redston contraptions, etc.
To find this: Make a world in Java Edition. Select type Buffet. Next, turn the World Generation type to Caves. Find Giant Tree Taiga biome and create the world. Next, fly up to the top of the world using /gamemode spectator. You will see that the mossy cobblestone rocks peek through the top bedrock. You will also see that the water ponds that naturally spawn in the world also break bedrock.