I had the embarrassment yesterday of having my Curve card declined with insufficient funds. I used a physical Visa card (the one that Curver was linked to) and it worked fine.
It wasn’t until I left the venue, that I realised I had set Curve Rewards to be my payment card (probably due to the Curve Cash announcements and me looking to see what I had on my Reward card (£x.00 to cover a bill of £xx.00!)
It struck me that this could have been handled better if Curve allowed me to spend my rewards, then charge any balance to a default actual card. Is that something that could be added perhaps.
I am not sure how the new cashback feature will work, whether it is in a similar way, then this could work for that area as well.