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.
I think upvoting would be allowed even if you are not a subscriber. Only downvoting would be limited in that way. And yes you could get around it, but small obstacles are surprisingly effective because people are lazy (ever try to get someone to switch to the Fediverse? Lol)
Oh, I was just saying how it works on Piefed right now.
It should be an option anyway for communities to implement that if they want.