Hi!
So today, I made three image posts, and all of them have broken thumbnails such as this one
and it seems to be showing up broken for other users too, not just me. I'm uploading images the same as usual and the thumbnails for my older posts were fine.
We had a temporary issue with generating different formats/sizes for existing images. I believe the issue is now fixed, our server is going through a backlog of missing files currently and regenerating them. I believe all broken images will be fixed within the next few hours.
Sorry for the inconvenience!