Cannot buy gift card

Hello,

I tried buying the 1st gift card on my website but after I put in my payment details, I just get a bad request error as seen here: https://snipboard.io/T10iHU.jpg

I am not sure what the issue is. Here is the gift card on my website (I am using Dokan multivendor plugin): https://pleazo.com/product/pleazo-gift-card/

Payment was tried via PayPal marketplace -> credit card as seen here: https://snipboard.io/VgbNMm.jpg

Can someone please let me know what the issue is?

Best,
Chris