Fans speculate that the author might be getting tired of being stuck with the same story.
While Kaguya-sama: Love is war manga continues to enjoy an enviable level of popularity and firmly remains among the top-sellers, not everyone is happy with the direction that the series has been going lately. Some fans took to Reddit to express their issues with the title and, surprisingly enough, they are mad for a very different reason than one might assume.
Generally speaking, when it comes to various anime titles, including the most popular ones, there're always some fans who end up dissatisfied with their visual style. Typically that might be a result of a rushed production cycle or a studio switch. The manga titles, on the other hand, especially the long-living ones, tend to be continually produced by the same people with a release schedule that is comfortable to them.
And thus, when they do come under criticism from their audience — it usually has to do with their stories either getting a bit unimaginative after the years or developing way too slowly.
Weirdly enough, the criticism that the fans direct at Kaguya-sama is primarily related to its visual aspect that, in the eyes of the redditors, is getting progressively staler with the recent chapters having a noticeable drop off in quality.
Some of the most notable issues include character's shading (that went from subtle but well done to completely inexistent), background art (that is getting less and less detailed with every coming chapter) and characters themselves (gradually becoming more expressionless).
All of that, according to the fans, takes a serious toll on the story by making its visual aspect look bleak and unentertaining with the sole redeeming quality being the fact that many people read Kaguya-sama for the plot rather than the visuals. And yet, in the eyes of the fans, this development might be a warning sign that potentially indicates that the author — Aka Akasaka — might be slowly getting tired of the title.