A 403 Forbidden error means that a specific right to access images on your site is denied.
Many security plugins such as Cloudflare have an activated Hotlink Protection. This will deny social platforms and other plugins and third-party tools to access the images on your site, so your images cannot be displayed and shared.
The following instructions help you to understand and deactivate hotlink protection:
If this still does not work out, you can check your website with the Blog2Social troubleshooting tool and check or send us the protocol to see, if there is another issue on your site: