In disproportionation reaction, oxidation state of one compound convert to the two compounds. one of higher and one of lower oxidation state.
ClO3−‌⟶Cl−+ClO4−7 ClO+‌⟶Cl−+ClO3+5 F2+2OH−‌⟶OF2+2F−+H2O In both the compounds, F−and OF2, oxidation state of F is −1. Hence, fluorine does not disproportionate. Oxygen also has −2 oxidation state, but in product its oxidation state becomes +2 in OF2 but still is −2inH2O.