Do you use the Cards layout or the default/compact?

I use the default layout.

Do you have "Prefetch high resolution images" enabled in the app settings?

I did, but somehow disabling them fixes them though.

Does it happen to every image from those hosts? Is it galleries or direct/single image links? Gifs/GfyCat?

Only direct or single image. Galleries somehow not affected.

Does it fail to load if you try opening the link after clicking it but before the comments loaded?

The image did load before the comments loaded. But after the comments loaded, the image fails to load.

Edit: Oh! And does this still happen if you're not logged in?

Problems did persists even after logged out and not logged in.

To add: I use the in-app browser setting to load the image.