I've observed two issues with certain type of images on lemm.ee.
The first issue relates to external avatars, both user and community. In the Android app Connect they are no longer loading and just show a spinner. Only the avatars of users and communities on lemm.ee itself are loading. It doesn't occur on web. And when using my lemmy.world account in Connect, all external avatars do load correctly. I think this started after the upgrade to 0.19.4.
The second issue is with metadata image, the og:image a page declares. This isn't always shown on lemm.ee. As an example a post I made with my lemm.ee account on a lemmy.world community.
https://lemm.ee/post/31969605 - Next to the title it just shows a generic external link icon.
https://lemmy.world/post/15406863 - Same post but now via lemmy.world shows the image that the target webpage defined as its og:image correctly.