@Mama_Cakes – if you’ve already unsubscribed from most or all of their posts, what is the problem? Is it that they include their nonsense in comments to other people’s posts also? If that’s the case, then “unfriending” wouldn’t be enough and blocking is the only way to not encounter them at all.
I blocked my perpetrator for a while, then there was family business that needed discussion, so I “befriended” him and started a group message. I think I have also blocked someone who abused a position of power and the unstable spouse of theirs, because we have friends in common, and I have most of my posts set to Friends of Friends because I’ve met some cool people through common acquaintances.