Hydrolysis of XeF4 will give XeO3. This hydrolysis reaction is a redox reaction. This redox reaction is an example of disproportionation reaction.
6XeF4+12H2O→4Xe+2XeO3+24HF+3O2
The oxidation states of Xenon in the reactant and product is
XeO3:Xe(+6)
XeF4:Xe(+4)
Hence, the difference in oxidation state is 2.