The reason it's lower on metacritic is mainly due to the fact that the critics rating is too high, imo. This leads to disappointed players leaving extra bad scores (i.e. 0/10) to offset the total score. In a way that's review bombing, but only as a reaction to the inflated critics' reviews (which I often suspect to be bought or bribed).
Usually the Steam reviews are a lot more reliable. As I said, metacritic's system is shit and encourages rating manipulation.