This method here will work.
- On this post, do you see the little rainbow Fediverse icon? Click on that. You're now looking at the original post on the server from which it originated. The post on lemmy.pethchat.org was federated to that server from lemmy.world where the post originated.
- Go to the search tool on your Lemmy server, and put that lemmy.world URL in there.
- The post will show up, and you can interact with it as it appears on your Lemmy instance.
Hope that helps! Let me know if you have any questions.