Not all games will land the same in all cultures across the world, and Steam is making a small change to review scores to reflect that. When accessing games with enough scores in your client’s selected language, you’ll see a separate score for that language alongside other metrics.
Valve published a news post for this change, which says that “when there are enough reviews written in a particular language, Steam will calculate a review score for that language,” with review scores displaying based the user’s primary language.
“What this means is that some languages may show more positive review scores, while others may show more negative ones, even for the same game,” the post explains.