Gmail can be a tricky inbox provider when it comes to emails rendering correctly! Klaviyo dynamically pulls images from your site through image source URLs from your integration. Sometimes these image source URLs may not have the http: or https: included, which can cause images not to render in Gmail.
To fix this issue, add |httpsize to the placeholder tag for the image. This will look different for each scenario, but here’s an example of what this might look like:
{{ event.product_image_urls_1|httpsize }}
The tags can be different but the filter will remain the same. Adding this placeholder tag should be the trick to solving this issue!