I can tell you it's on a block list we vetted and trust and which documents the steps taken before a server makes it onto the list.
The fact the problematic accounts have been removed is good, I'd suggest the server owner (or a moderator) flags that to IFTAS (npub1y2r…kvzk) so they can then review removing it from the list.
We have our own process for how we handle instances on blocklists with existing follower / following relationships but the vast majority of the instances we block that are on the blocklists we choose to use have no historic interactions.