I've read at another forum the film was deliberately downvoted by "Team Johnny Depp" because Amber Heard is in it. No idea if that is true though, but I wouldn't be surprised.
It was very, very obviously downvoted through some orchestration or campaign of some kind so that seems very plausible. It has 94% 1/10 ratings on imdb, which is basically impossible if it was from "normal" users voting, there's never going to be a unified vote on a 1 out of 10 scale that extreme from 17,000 votes. As a baseline, Manos: The Hands of Fate has 66% 1/10, and even that is unusually high. Cats has 45% 1/10.