Hello,
I create a new test website, with no other plugins.
I f I use another them that Divi, it’s ok my images are not blurry. So, I asked Divi if they can help, here are their answer : “Actually, the mobile version displays a size of 320×221. But your image is of size 300×207 as shown below
https://allasimmo2.stephanieantoine.fr/bugestatik/bug_estatik.png
As the contents are generated by the plugin. I have no idea if there is a way to add and use a large image for the Mobile version as I have not used this plugin personally.”
I saw that you have already check this problem : https://www.ads-software.com/support/topic/blurry-photos-on-mobile/ The issue was with Divi too.
You say that your plugin is fully compatible… I think that you have an issue with Divi.
Many thanks for your quick return.
Regards