In the reaction,
2FeSO4 + H2SO4 + H2O2 → Fe2SO43 + 2H2O
The oxidizing agent is
FeSO4
H2SO4
H2O2
both 2 and 3
H2O2 is an oxidizing agent, it is reduced to water
H2O2−1 → H2O−2
Oxidation number of oxygen decreases.