There's some relevant discussion here and in the thread linked by ernest in that post here. I don't want to give any wrong information, but I don't think activitypub has a spec for downvotes/reduces/dislikes, just likes and shares (boosting). So on mastodon dislikes definitely aren't federated. I believe for lemmy, they federate between lemmy instances that have them enabled, but for kbin they are local to your instance.

[–] effingjoe@kbin.social 1 points 1 year ago* (last edited 1 year ago) (1 children)

I appreciate the additional information, however, a link found in the codeberg link you provided leads to this comment from earnest:

The up arrow is the equivalent of a boost on Mastodon, adding to favorites is represented by a star. The down arrow is equivalent to the Dislike button on Lemmy and Friendica, Mastodon probably doesn't have an equivalent (Dislike will be federated this week). Compared to Lemmy, it works a little differently, as the up arrow there is the equivalent of a favorite.

The comment activity can be checked by expanding the "more" menu and selecting "activity"

This seems to imply that downvotes (reduces) are federated. (And notably, upvotes are now "stars" "boosts" are, uh, "boosts"; this was changed since the linked comment was made)

Or am I totally missing something? That's always and option.

[–] e569668@fedia.io 1 points 1 year ago* (last edited 1 year ago)

He did say it would be "federated this week" but in the next comment in that issue he made he said that changed "but it turns out it's not easy, and I wouldn't want to make such a big change hastily". I don't think anything has happened since. I definitely almost never see any reduces over here on a different kbin, so I think it's still the same. There is still some discussion in that issue, someone just posted they have a PoC of doing it in a fork for instance.