I see some posts while sorting by hot that are as old as 2 years. I sincerely doubt that those posts would show up while sorting by hot, and I’m not even sure there are posts that old on lemmy. I saw a post that had an article written 2 weeks ago, and the post said it was 2 weeks old which leads me to believe posts show the age of the link
If you go to your lemmy instance on the web and check the post, does the issue show up there too? If so, it may be a lemmy bug that needs fixed on their side and not mlems.