This is default behaviour of Nextcloud, which does not work within Discourse for some reason. It is discussed on the Nextcloud forum here. Thanks for any guidance or suggestions!
What’s the status on this? I’d love to be able to just dump a nextcloud link and then see it as a picture in discourse! I suppose we need a button in nextcloud which copies the preview link with added ?format=.jpg by default in the sharing tab?
I’d like to be able to do this too. Hmm… let me do a test. Ok, when I get the sharing link and paste it, it becomes oneboxed. This is fine for me, though of course it would be nice if it showed up more prettily.
Here’s the same image with the ?format=.jpg appended.