no_flag.png insecure | WordPress.org

Hello,

I have problem mentioned below. Somewhere in the plugin it’s called no secured img. Is any solution for this?

Mixed Content: The page at ‘https://www.retrofitguru.com/cs/’ was loaded over HTTPS, but requested an insecure element ‘http://3.123.173.30/wp-content/plugins/woocommerce-currency-switcher/img/no_flag.png’. This request was not upgraded to HTTPS because its URL’s host is an IP address.

The page I need help with: [log in to see the link]