Potential Threat from a Serial Downvoter

Look, I don't know whether this will count as a major issue or not, but there's this one user (who for the purposes of this issue I will not mention by name) has been downvoting a significant amount of the casting suggestions in my story "Deceased Celebrities Face Claims Sorted by Year of Death". Most the deceased celebrities that were added by myself and several other users were seemingly downvoted by this user for no apparent reason. Have any of you encountered a similar situation where a user of group of uses will seemingly downvote most casting suggestions for no apparent reason? Please let me know. Thank you.

I dunno if this one counts, but once there were these guys, who, for whatever reason downvote whenever i casted a japanese actor/actress on my stories.

And fyi, in your story that you mentioned above ("Deceased Celebrities Face Claims Sorted by Year of Death"), there's this one guy who downvote japanese celebs that were suggested in a specific year of death, was it the guy you mentioned above or it's another dude ? Because once, most of the japanese celebs that were suggested (including the ones that i've suggested) on the "Face Claims sorted by Country" story got mass downvoted by the guy and his clone accounts for no reason at all (and yes, i won't mention this user's name).