This post knows where you're viewing it from (Lemmy doesn't proxy external images)

https://lemmy.ml/post/3180965

This post knows where you're viewing it from (Lemmy doesn't proxy external images) - Lemmy

An external image showing your user-agent and the total "hit count" [https://trilinder.pythonanywhere.com/image.jpg]

So what is happening if I don’t see an image?
it is because the website providing the image is overloaded and cannot create an image.
You just have to reload the image and eventually you will see one.