The mod banning these users is the same mod who made the posts they downvoted. This is mod abuse, turning the downvote button into an auto-self-ban button.
The message is “If you disagree with me, you will be banned”
Monitoring and banning users for using lemmy as intended to signal boost your opinion should be grounds to have all mod privileges removed. This behaviour undermines the integrity of the server and the wider fediverse.
You need to be a community moderator to see the votes on your own community on Piefed.
You can also use Lemvotes to see votes on a post, but not piefed because rimu defederated from them.
Found it, thanks. I replied to my own comment with a couple screenshots before I saw your reply.