There are at least two permanent fires in the current community build world. I'm on a galaxy on5, andy 6.2, SC v2.0. I assume the other players can see them, too. If they knew where to look. They look like the remnants of a forest fire and are likely at the tops of the burned out trees. They are a flame block without the original fuel block. They cannot be broken and do not catch the hero on fire.
I have seen these before, on earlier versions and older devices, too.