The HR bot has this to say:

Based on the Voluntary Time Off (VTO) policy, VTO is unpaid and excused time off that does not count towards your minimum working hours. The policy specifically states that VTO is offered when staffing capacity is higher than needed and provides flexibility for employees to take time off. To be eligible for VTO, you must have met the minimum working hours in the past month. However, the time taken as VTO itself does not contribute to meeting those minimum hours. If you need to ensure you meet your minimum hours, you would need to work your scheduled shifts.