It works in a pretty neat way:
We’ve decided to create a new kind of OpenGraph tag—the same kind of tags you have on your website to determine which thumbnail image will appear on the preview for the page when shared on Discord, iMessage, or Mastodon. It looks like this: <meta name="fediverse:creator" content="@[email protected]" />.
via: https://blog.joinmastodon.org/2024/07/highlighting-journalism-on-mastodon/