I saw this voucher code as a perk from Revolut - tried applying it to my partner's existing account and it seems to work!
e.g. The standard box for 2 people containing 3 dishes per week costs £29.99 so will be down to £14.99 per week for 4 weeks.
You should be able to cancel after the 4 weeks if you wish.
T&C are here for your reference assets.revolut.com/off…htm
I'm not sure if you actually have to have a Revolut card - my partner's Hello Fresh account is linked to PayPal. It seems the discount will be applied anyway. I should find out within the next week if it doesn't work and will update this deal.