Using flint & steel on fire will take durability, meaning setting x blocks on fire will result in x+y durability being taken, with y representing accidental clicking on already-on-fire blocks. Similarly with fire charges: Having a stack of charges does not mean setting 64 blocks in a row aflame, but 64-y blocks.

Phrased differently, when setting fire to blocks by holding down the use button, less than the expected number of blocks are set on fire.

Bug: Using flint and steel or fire charges on preexisting fire uses up durability/fire charges

Expected Behavior: Using flint and steel or fire charges on fire blocks results in no change in durability or fire charge count