XeO$$_4$$ molecule is tetrahedral having:

Xenon uses its four $$sp^3$$ hybrid orbitals to overlap with the $$p$$ orbitals of four oxygen atoms.

Because oxygen is divalent, each $$Xe-O$$ bond is a double bond. Xenon utilizes its four remaining unpaired electrons in the $$d$$ orbitals to form $$\pi$$ bonds with the $$p$$ orbitals of the oxygen atoms. These four $$\pi$$ bonds result from $$d$$ (Xenon) and $$p$$ (Oxygen) orbital overlaps.

Hence, $$XeO_4$$ contains four $$p\pi - d\pi$$ bonds.