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.
That’s not “not sharing an interest”. That’s being actively antagonistic and arguably harmful to those in the community. For at-risk communities, that’s a hard line to parse sometimes and it’s understandable for moderators to be less lenient in their decisions. A community about a money sink by the world’s richest idiot doesn’t really have the same concerns.