Is it permissible for a person to receive a salary from a government entity that approved his appointment, then asked him not to report for duty due to a lack of work for them, while he wishes to go to them once a week, and this continues for a year or more?

The contract concluded between the employee and the employer governs the employee's actions, as Allah Almighty says: ﴿O YOU who have believed, fulfill [all] contracts﴾ [Al-Ma'idah: 1], and as the Prophet ﷺ said: "Muslims are bound by their conditions." If the employer or an authorized official permits not attending work, then the action is permissible and the salary is lawful, because the employer has the right to grant the salary without work.