HTTPS broken image link

https://etczone.com/residential/security/security-systems/
On this page you can view the Apple version image is broken. This is because it’s looking for the image in https://domain.com because our site is secure but the domain where the image is doesn’t use https://. Similar to this issue, https://wordpress.org/support/topic/https-in-external-links?replies=5 , where you’re correct that your code should just be // but in this case I guess http needs to be required?

https://wordpress.org/plugins/wp-appbox/