There are plenty of things that can cause fires that are not oxygen, and don’t contain oxygen.
The halogens, Fluorine and Chlorine in particular, are powerful oxidizing agents on their own and can produce flames in the same manner as common flames.
Here’s a report on the spectra of flames produced by combustion in a Fluorine atmosphere (PDF warning).
There are plenty of things that can cause fires that are not oxygen, and don’t contain oxygen.
The halogens, Fluorine and Chlorine in particular, are powerful oxidizing agents on their own and can produce flames in the same manner as common flames.
Here’s a report on the spectra of flames produced by combustion in a Fluorine atmosphere (PDF warning).
Now I need a NileRed video on combustion in a fluorine atmosphere.
(Also, props to your username. I see you, fam.)