You can see this from the root page of our community:
https://lemm.ee/c/eurographicnovels

In which the posts that link to Imgur as their thumbnails now display the ‘offsite’ arrow pointing to the upper-right. Note that all Imgur-based behavior seems otherwise fine, for example you can click on the thumbnail and the full image will properly display, and the contents of the posts themselves seem unaffected.

Browsing around other lemm.ee communities, it seems that all other thumbnail post imagery is functioning normally as long as it doesn’t link to Imgur.

Hope I explained that clearly!