I’ve found that several papers on the daily papers page, including mine, have been spam upvoted by bot accounts over the past few days. Here are some papers that I found have a substantial amount of botted votes:
List of Botted Papers (Google Docs) (I can’t directly place more than two links in a post for some reason)
There are probably other papers as well, these are some of the only ones I checked. It’s the same few accounts that are spam upvoting all these papers.
I think you should have to verify your email before casting a vote, and also have the option to directly report accounts for spam.