Google has announced that it will eventually drop support for mixed content in the coming months. Mixed content is when a website is served over HTTPS but includes resources (such as images) over HTTP.
In it’s current state this is allowed but typically a warning is shown to the user that not all content is secure. Going forward this will no longer be the case for Google Chrome.
Starting in December of 2019 (Chrome 79) Google Chrome will introduce a feature flag (defaulted to off) to disallow all mixed content. It will attempt to upgrade resources to HTTPS if they happen to also exist. In future releases by Google Chrome the mixed content will simply not be loaded.
It’s a poor user experience to have mixed content as well as it not being as safe or secure to the user. Mixed content should be addressed as soon as possible to avoid potential disruptions, should any exist.
More information about this change can be found at: https://blog.chromium.org/2019/10/no-more-mixed-messages-about-https.html