

A discoverable non-banned account. Not from “ghost accounts”. If a server creates a massive amount of accounts to use them to vote, you can see that a small server has a disproportionate amount of registered accounts too, which probably will be otherwise inactive. Then you can reject votes from that server.
The post you replied to comes from a different instance than your own, so does my answer. When you’re logging into your instance, the view of their and mine posts are both remote to you.
Sometimes in Mastodon you’ll only see the specific post that you’re opening a link to directly, not other posts before or after. This tries to fix that.