Is it just on my end? All other instances i have tried (.world, .ml, sh.itjust.works, db0, even hexbear) are displaying thumbnails correctly. I have tried opening lemm.ee in chrome, changing my dns etc.
I think it's related to this issue (re: lemm.ee is fetching and caching images (to improve performance) , but often get is throttled (because the Lemmy's cache implementation was not designed to work with larger Lemmy instances ), which results users seeing broken images).