(I am OP) I now can't access this post from my original instance. I wanted to edit the title and I forgot that can be done on Lemmy, so I deleted the post. However it only deleted it from my home instance where I now can't access it. I decided to check if it's the same with comments, and yeah, they don't get deleted from other instances either. So as a result, this post is now only unavailable on lemmy.sdf.org. :-/
You could normally see the original post by clicking on the rainbow federation icon.