When NPCs use BBQ grills and Propane grills (usually happens with ovens too), the tile catches on fire. It then leads to a fire akin to CDDA's fire to happen, which spreads forever, even on road/non-burnable tiles.

Please, for the love of God, either disable the NPC's ability to use BBQs, or put a disclaimer that the fires will happen by accident and that they will spread everywhere. It's not fun disabling fire spread.