"Gift Card Design" images should be 1125 X 582 px.
These images can be edited by going to Settings > Gift Card Designs in the platform.
To view the current image size of the selected gift card design, you can right click > "Inspect Element" on the image or utilize Developer Tools (F12)
If further assistance is required, submit a ticket to Punchh Support. (For help submitting a ticket, click here)