@julian To be honest, I think it might be worth breaking compatibility with Mastodon, although if you can get it to work well with Lemmy and/or Kbin that would be ideal for this. Mastodon deviates from the spec in a lot of key ways, so as long as you keep closer than it to the spec, you get to point out that no, you're doing it right, it's Mastodon that's doing it wrong or missing this thing.

@julian Iceshrimp classic shows the link as https://community.nodebb.org//community.nodebb.org (and links to that) and assigns it "nofollow noopener". I think the page doesn't render unless you use JavaScript anyway so it shouldn't affect search rankings?