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.
With a moderately careful user and a slightly more robust implementation it would have done exactly what it was meant to do, and what my ultimate goal is - which is to enable (but not guarantee) a longer term, archival level of privacy. The concept is not perfect, but it is a massive improvement, which could lay the groundwork for a future framework where user privacy and community management are both handled in more elegant ways. Without going into too many details, I am extremely well aware of how data gets linked to users in this way, which is why I am so adamant and vocal about this particular threat. I am not just sounding an alarm to keep my skin smooth.