I think being like “sorry, we’ve reverted votes from recently signed-up accounts because we can’t distinguish them” seems fine. Also, in my experience abusive voting patterns are usually very obvious, where people show up and only vote on one specific comment or post, or on content of one specific user, or vote so fast that it seems impossible for them to have read the content they are voting on.
I think being like “sorry, we’ve reverted votes from recently signed-up accounts because we can’t distinguish them” seems fine. Also, in my experience abusive voting patterns are usually very obvious, where people show up and only vote on one specific comment or post, or on content of one specific user, or vote so fast that it seems impossible for them to have read the content they are voting on.