How does downvote disabling work between federated instances?
Context: I use Liftoff as my mobile client. I have accounts on blahaj.zone and lemmy.world. When I'm logged in on blahaj.zone on desktop, there is no downvote button. It appears on Liftoff.
It makes it so that downvotes just won't be accepted on that Federated server. You can still downvote the content from servers that do but it won't count on the original servers.
Also to answer your question no they can't downvote your content from the other servers, on instances that have downvotes disabled downvotes won't be able to go through because they are disabled across that instance and therefore can't be used by users of that instance.
It can also be used as a form of semi-covert harassment. For example, in an early instance, every bit of content posted by or in support of transgender people would get hit by a barrage of downvotes from brigaders using otherwise inactive accounts. Hard to moderate that without just disabling downvotes entirely.
It depends. If the vote is in a community that is hosted on an instance that has disabled downvotes, these downvotes will not be accepted and only maybe your own instance might display it. If the community is hosted in a server that has downvotes enabled everyone but the instances with disabled downvotes will see the downvotes.