Because, in XeF4 The central atom is Xe
Thus according to the VSEPR Theory, Xe contributes 8e-
While the 4 x F contribute 4e-
Total VSE = 12
and therefore total VSEP = 6
The molecular geometry is therefore square planer( based on octahedral) or square pyramidal,
having the fluorine atoms directed towards the four corners of the square.
F-Xe bond angles are therefore 90o or 180o and the lone pairs are on the opposite sides of the molecule (at 180o from each other) to minimize lone-pair: lone-pair interactions