All instances in the Fediverse work based upon the "ActivityPub" protocol. This is true for all Lemmy instances, all Kbin instances, Beehaw, and even Mastodon. If it's in the Fediverse, it's runs on ActivityPub under the hood.
As such, any "activity" that any user from any instance does (I.e. likes/upvotes, dislikes/downvotes, boosts, etc.) Will sync with all other instances provided they are federated, syncing properly, and support the activity in question (not all instances support all activities or process them the same way).
Ergo, in theory, the likes you see on a post will be from all instances that support likes, likewise for dislikes.