Yes, the voucher amount is insured by Dutch Travel Guarantee Fund “SGR” (https://www.sgr.nl/guarantee/). This means that the SGR guarantees that consumers will receive a refund if a travel organization is unable to meet its payment conditions.
With this voucher, you don’t have the risk to lose your money if the travel organization goes bankrupt between the cancellation and refund of your journey.
Fortunately, Sunweb Group is a healthy company, but it’s an important extra security, especially during these times.