That happened to me on a community a while ago. I found an article that I thought might be of interest so I linked it and wrote some commentary regarding it.

It was rejected and I was told the reason why was that it had already been posted. Then the moderator who rejected it sent me a note saying I should do better next time and check the community memories.

So I did that as well as went through a ton of backposts just to be sure and that particular article was never posted.

I left the community.