Scientific Reports (Nature), 2013
However, "recently commented" is not a standard, formal academic term. I’ll interpret your request in the most useful way possible and provide a from credible research that addresses activity-based ranking (especially recency of comments as a driver of visibility/user engagement). Recommended Paper Title: "The Dynamics of Information-Driven Attention on Social Media" /recentlycommented
"Ranking Comments on Social News Sites: A Novel Approach Using Comment Recency and Thread Structure" (J. Lee & S. Kim, Expert Systems with Applications , 2019, 128, 56-67) Scientific Reports (Nature)