Something is wrong with images/pictrs

On some communities the header image and community logo is broken, e.g. here: https://lemm.ee/c/idm

I'm the mod there, I haven't changed images since I started the community, a year ago. If I click on the Edit community button, I can see both images on the sidebar.

If I comment somewhere and link to external image with the markdown syntax ![](...) images not showing up. This works in post bodies, it only affects comments.

Created a test post here, you can see the image in the first comment is not visible: https://lemm.ee/post/38021843

Edit: This may be related: https://lemm.ee/post/37717282