I’ve had a very similar issue, and I believe many other developers can say the same.
My game was disliked manually by someone creating several different accounts, by several I literally mean over 75 (This is verified, as he was reported to me via discord making said accounts with similar names by people in-game) I should also mention this person was banned for trolling, bypassing the filter, and being toxic to visitors in general. These mass amounts of dislikes would appear over a span of three days, and has brought my game to a 69% ratio, which looks terrible and I cannot get out of it as SO many people have now voted on it. It still happens from time to time, but luckily in smaller amounts, and most of my ratings now are actual people.
I tried to make a newer topic on this issue, and suggest something about the like/dislike option, but nothing has changed. I think fixing the issue with this like to dislike ratio issue is one thing Roblox should try to do this year, as it would be beneficial to many developers.
Links:
OP of the described topic: How about we introduce a Feedback System when disliking games?
My reply to said topic: How about we introduce a Feedback System when disliking games? - #10 by BIoximus