Valve published a blog post today outlining how a recent Steam code change meant to fix a discoverability bug inadvertently changed the way Steam algorithmically recommends games, harming some devs' traffic.
Most notably, Valve claims that traffic from the "More Like This" recommendation engine on every Steam store page did drop noticeably for two weeks in early October, but that it "recovered around October 19th, and has stabilized since."
This lines up with the dip that devs like Grey Alien Games' Jake Birkett documented last month, and some people are continuing to see. Valve chalks the short-term issue up to an accidental algorithm change that caused the "More Like This" widget to recommend the most popular games on Steam that share a tag in common with a given game, rather than the most similar games.
At the same time, the company was testing a recommendation algorithm change that also caused some unforeseen traffic drops, and Valve says it will continue to do these sorts of things as it works to improve the storefront.
However, as Birkett notes, many indie games have continued to see low referral rates all the way through October and November, meaning that the algorithm change has led to likely permanent decreases in referral traffic. (Though some devs have likely seen increases, too.)