To create a product post on Facebook (with a product page link, with a clickable image, etc.), we should send a product link to Facebook.  In other words, a special Facebook bot goes to this link and checks the availability of special meta tags. Using these meta tags, Facebook independently collects a post (picture, link, site name, etc.).
That’s why we recommend to enable “Add meta picture” toggle.

If you see small images published by Social Rabbit plugin on your Facebook page, it means that the featured image of your product is of small size.
You can read more about Facebook image requirements at the following link:
https://developers.facebook.com/docs/sharing/webmasters/images/