Saudi Arabia has now ditched the Hijri calendar which was the only recognized calendar since the establishment of the Islamic state of Saudi Arabia a

Answer

There is no reason for surprise. The Kufr regime of the Saudis has ditched and abrogated the entire Shariah. The Shariah has been replaced with kuffaar law. The Saudi regime is an Agent of Iblees and the Bootlicker of America, hence the kuffaar calendar has been adopted.