You may see all data in raw format (including downvotes) on steemd.com blockchain explorer.
Just change "steemit" on "steemd" in URL of your steemit.com article and you will get the full data.
For example, here is this article link on STEEM block explorer: https://steemd.com/steemit/@wpalczynski/steemit-removed-the-ability-to-see-who-downvoted-posts-it-seems-that-this-platform-is-not-moving-in-the-direction-of