Didn’t find where it was previously discussed, but on this forum for some time the Onebox functionality of Discourse no longer works and this means when dropping in a link to some external website we do not get a nice preview generated from OpenGraph metadata on that page.
I recently spun up a Discourse forum myself using Yunohost at https://discuss.coding.social and just now observed that I have the exact same problem.
Nowhere in the logs (at least the ones available in the UI’s) of both Yunohost or Discourse can I find any error relating to this problem. Also, since I installed the forum I haven’t updated anything, and I don’t see anything about an auto-update. And Onebox used to work on the fresh install. It is a mystery why now it doesn’t.
So I expect there’s more nasty deep digging to be done to find and solve this problem, and that likely we face a Yunohost-related issue. Personally I find the generation of those oneboxes very useful and would hate it if I didn’t get it to work. On the whole I am not really satisfied how Yunohost has disabled the native update functionality in Discourse.
I’ll keep you posted if I find anything more related to this problem.