If a flat world is created with fire as the top block for the preset, the fire will float in the sky.
Comments 2
Might have been MC-217802 then. Will resolve this report as "Cannot Reproduce" since you are saying it only works in that old version.
MC-222540
Fire sky
Resolved
Cannot Reproduce
0
It turns out this glitch only works in 21w08b. However, if a world from that snapshot with a fire sky is loaded, the fire is still floating.