Hi Gregor,

Thank you for contacting us about this and for sharing all the really helpful details!

I can confirm we have reproduced this issue, and it appears to be a bug on our end. The coupon is valid and the discount is applied correctly. The warning is a false alarm that shows up on coupon links for pages where a testimonial has no profile picture.

We have a fix in review, and I'll let you know when it's fixed.

Kind regards,

Michael