From Scientific American : How does a flame behave in zero gravity?
”...neither buoyancy nor convection occur in a zero-gravity environment such as space. Consequently, the combustion products accumulate around the flame, preventing sufficient oxygen from reaching it and sustaining the combustion reaction. Ultimately the flame goes out. [emphasis mine]
”...In the early years of the U.S. space program, tests were conducted on unmanned missions to ascertain what would happen to a flame in a pure oxygen environment under weightless conditions. Researchers learned that flames extinguish themselves.”
Before the flame goes out it is spherical in shape—see photo at link.