Crafting bamboo into scaffolding gives you 8 times the furnace fuel for free

Can confirm in 1.17.1.

crafting logs into planks gives 4 times the fuel: https://minecraft.fandom.com/wiki/Smelting#Fuel

regarding the sanity of scaffolding, I guess you could argue that the string makes the burning more efficient in the same way that a wick makes a candle burn more efficiently

in terms of gameplay balance, I don't think this is overpowered since crafting large amounts of fuel requires more player input than, for example, an AFK bamboo farm

I can confirm this in 1.18.1. Here's a code analysis along with a potential fix regarding this issue.

Code Analysis:

The following is based on a decompiled version of Minecraft 1.18.1 using MCP-Reborn.

net.minecraft.world.level.block.entity.AbstractFurnaceBlockEntity.java

public abstract class AbstractFurnaceBlockEntity extends BaseContainerBlockEntity implements WorldlyContainer, RecipeHolder, StackedContentsCompatible {
   ...
   public static Map<Item, Integer> getFuel() {
      Map<Item, Integer> map = Maps.newLinkedHashMap();
      ...
      add(map, Blocks.BAMBOO, 50);
      ...
      add(map, Blocks.SCAFFOLDING, 400);
      ...

The minimum burn time needed to smelt one item is 200. If we look at the above class, we can see that a singular piece of bamboo provides a burn time of 50, and a singular block of scaffolding provides a burn time of 400.

Scaffolding is constructed using six pieces of bamboo, and we are granted six blocks after crafting it, therefore one piece of bamboo is worth/equal to one block of scaffolding. Six pieces of bamboo provide a total burn time of 300 and six blocks of scaffolding provide a total burn time of 2,400. Despite both items being worth six pieces of bamboo, the scaffolding provides eight times as much burn time, which doesn't make much sense.

Potential Fix:

Since one block of scaffolding is worth/equal to one piece of bamboo, scaffolding should have a burn time of 50. Simply altering the appropriate and existing line of code to reflect this, should resolve this problem. The correct piece of code within its class should look something like the following:

net.minecraft.world.level.block.entity.AbstractFurnaceBlockEntity.java

public abstract class AbstractFurnaceBlockEntity extends BaseContainerBlockEntity implements WorldlyContainer, RecipeHolder, StackedContentsCompatible {
   ...
   public static Map<Item, Integer> getFuel() {
      Map<Item, Integer> map = Maps.newLinkedHashMap();
      ...
      add(map, Blocks.BAMBOO, 50);
      ...
      add(map, Blocks.SCAFFOLDING, 50);
      ...