Zelenskyy promuove il comandante in capo dell’Ucraina Syrskyi al grado di generale

Can anyone with knowledge explain why the CnC wasn’t already a general? Is this an appointed position regardless of status (military v civilian)?

For those who are not aware, Colonel General is 0F-9 in NATO designation, General seems to be the OF-10 rank, equivalent to Field Marshall (a rank only used in Commenwealth militaries in times of war).