Saw this challenge in the app. Only available for Sydney locations. Below are copied instructions from the app. Full T&C's on Shopback.
How to Play:
Purchase any voucher from ShopBack In-Store using your Mastercard®
Receive $5 bonus cashback (added to your account with 72 hours of purchase)
Limited redemptions apply
Note: Your challenge progress will only update shortly AFTER your regular cashback tracks
Purchases from ShopBack Gift Cards are not eligible for the bonus
ShopBack In-Store vouchers are currently only available for redemption at locations in Sydney
Terms & Conditions
Receive $5 bonus cashback from ShopBack when you purchase any voucher at ShopBack In-Store via the ShopBack app using Mastercard® (the entire value of the purchase must be paid for using your Mastercard® credit or debit card to qualify) between 12:00am AEDT on the 14th December 2021 and 11:59pm AEDT on 31st December 2021 (unless the offer is modified, extended or terminated prior). Transactions made directly at venues do not qualify.
Offer is available to new and existing ShopBack and Mastercard® customers and only available through the ShopBack app.
Only purchases made after you ‘Start’ this challenge will qualify for the bonus $5 cashback.
Limited redemptions apply.
Bonus is limited to one per ShopBack account. Additional transactions do not qualify for additional bonuses.
The $5 bonus cashback is in addition to the regular cashback you’ll receive for buying a voucher at ShopBack In-Store.
That's quite the title.