Lemmy is totally open to vote manipulation. If I want to harass you, I can create accounts on multiple instances and downvote every post or comment you make with 100s of accounts. That might be a little obvious, but you can totally swing policital discussions with a small network of accounts here (just give everything pro palestina 40 upvotes and downvote every pro israel post 50 downvotes) and local admins have no method of checking that you are using multiple accounts. All they get is the federated upvote.

And, well, the whole Nicole situation also shows that there are huge holes in spam protection.