Update: Air Serbia will allow you to freeze your ticket and change dates later on for travel through 12/31/20. Even if the fare is higher, no additional amount will be owed.
They say that passengers can choose from free rescheduling of travel dates through 12/31/20, a free change of destination, or a refund.
Were you booked on Air Serbia to Israel? Will you reschedule your travel dates or try to get a refund?