I’m still disappointed about that and tbh I dont think it’s likely to be reverted.

I’ll use it if I want a very specific amount of an item that I can craft more than I need of - otherwise I’ll do it manually

That’s fire - lava extends in a 3x3x1 area centered on the block directly above it, and a 5x5x1 area centered directly 2 blocks above it - if any of the blocks within that region are air and are next to something flammable, then it lights on fire. In this example, it extends into the slabs, but it’s ok because none of it is air