"Recent review score" will show positive ratings for the past 30 days.
Valve has announced that Steam will be updating user reviews in order to show the most recent reviews and scores. This is being done in order to reflect how players currently feel about a game, as they often change over time with patches, updates, and dlc. In the post, Valve wrote that it is difficult for newer reviews to be seen and voted on in order to be determined "most helpful," with reviews labeled as such often describing "an outdated view of a game that might have changed dramatically over the course of Early Access or post-release development."
"That review score that appears at the top of a product page didn't always reflect the dynamic nature of the game," the post reads. "We'd previously only been compiling an overall score using a simple calculation of the percentage of all reviews that were positive. This let us be really transparent in how the score was being calculated, but didn't accommodate cases when a game has changed a lot (for better or worse) over time."
In order to reflect the current view of a particular game, a "Recent Review Score" has been added, and will show the game's positive percentage of reviews over the past 30 days (assuming the game has been on steam for 45 days or more and has enough reviews posted in that time frame). The overall score will still be present.
Some other changes include a "Summary" tab that focuses on recent helpful, and recently posted, reviews as well as a checkbox for easy disclosure if you received a free copy of the game.