I have seen that in many articles of 2D materials calculations that VASP is the most used one among DFT codes. Could please explain to me why?
I am not aware of any reason (and don't see) why VASP is more popular than its contemporaries for 2D materials. VASP does have some features that other packages don't, but it also has its own drawbacks. You can refer to this discussion where differences between the two most common packages (VASP and Quantum ESPRESSO) are outlined.
In general, I have come across more papers that report calculations done on VASP, rather than say QE. This is not specific to 2D materials.