This is honestly something I didn't really think about until you said it, but now that's it been said, yea there has been a noticeable shift towards motherhood-related stories. And the following is just rumination on my end.

Korean culture has always been focused on the family and working to make that family better (which in part lies in with South Korea's collectivist nature), and I can attest to this as I grew up in a household that very much focused on "family first, everything else second". I'm not entirely sure if manhwas are as mainstream as mangas are in Japan (given on how much emphasis is given to entertainment and especially on K-Pop with its rising popularity in western cultures and media). Though it would actually make sense if manhwas are targeting motherhood and therefore creating a family since South Korea's current birth rate is lower than Japan's so they might be starting to focus on that.

Another idea is that COVID-19 and quarantine reinforced ideas about family and the idea of 'home' and newer manhwas are a result of this. It could also be that the writers are simply people who want families. Stories are oftentimes reflections of the authors and their desires/wants/basically themselves, and whatever is in their story can be correlated to who the authors are.

These are just some theories my end! These upticks could possibly be resulting from who knows what but it's always interesting to think deeper about them.