Fediverse

So let’s say instance A and B are defederated from each other, but both are federated with instance C. After a user from A posts something on C does every user from B get to downvote everything?

Yes. Instance A will not see the downvotes from instance B, but instance C would. Also, anyone federated with all 3 would see the downvotes from B for content posted by someone on A.

The only defense is that mods and admins can see the votes and, if something like that is suspected, they can take action (ban the accounts, mods report the behavior to admins, consider defederating from instance B, etc). Seeing a pattern of mass-downvotes only from a particular instance would be considered a red flag for most admins.

This scenario is less likely than what we see in practice, though, since the overhead to create an instance and the "eggs all in one basket" make it easy to take action against (admins would quickly coordinate to block that instance). Tools like Fediseer would also be used to censure that instance and bring its behavior to light.

In the wild, it's far more common for them to just spin up a bunch of accounts across "good" instances (particularly those without registration applications) and coordinate.

One example of that: https://dubvee.org/post/1878799

I still don't understand why I should care about the karma system. I didn't care when I was on redditt. People must generally like my comments, because I was net positive last time I checked.

Why does it bother you?

If it helps to add: ditch the analogy about the Fediverse being like email, for the level of understanding that you are seeking. Instead, consider it like a bunch of ships (hehe, free traders and... otherwise), each passing messages around.

When A posts to C, A knows about it, but more importantly everything connected to C also knows about it too. A copy of the message has been shared with all the partners. So yeah, thus B knows about it too, despite the lack of direct connection to A.

Although then when B sends C the downvote action, A is not told, bc of the defederation. So everything connected to C and B knows about the downvotes, with the exception of instances that have disabled downvotes entirely, and those who ignore all messages coming from B, plus those who likewise ignore all messages coming from A.

Where it starts to get tricky is that defederation does not have to be symmetrical, although ideally it always would be. In theory, and it has most definitely happened, messages sent from one instance to another can definitely be influenced by an asymmetrical pattern of defederations.

I wouldn't worry as much about Alt-Right conservatives here - they tried but couldn't get a foothold, and after being defederated from all instances eventually collapsed internally, and went to Truth Social.

Here, we ironically have much more to worry about from the Alt-Left that uses identical patterns of behaviors, just ostensibly on the "left".

Just use the search function and sort by Top All Time and you'll find everything you need. But if it helps, here's my own (successful) Petition to defederate from hexbear.net on Discuss.Online, making that USA instance safer to recommend to aid people fleeing Reddit. You can click the links and read with your own eyes examples of those admins being caught lying to other admins, and one case of a mod tripling down in saying how they wanted to kill someone for a simple misunderstanding of a scenario in a game (although do such details matter in the slightest?) - that one was on lemmy.ml though. And btw in case it helps, How do I block users from an instance of my choice? (TLDR: it's super difficult, not really entirely possible without jumping through some rather hefty hoops, but with enough effort or sacrifice of freedom of other choices it is possible).

AFAIK yes, users from instance B can downvote the post, but the downvotes won't federate to instance A, so only users on B and C will be able to see them.