With version 2.4.0 we introduced the non-strict mode for the insecure content check. When activated Leankoala does not alert if images are not transferred via https on a https page. We introduced this mode because browsers work like that. If an image is „insecure“ the browser loads it nonetheless.
In our opinion, all the content should be transferred via HTTPS. This is why we do not recommend this mode. Additionally, we believe that sooner or later the browsers will end their non-strict mode as well.