That's why I am addressing manga readers specifically. Pace is not the same thing as a release schedule. This arc will be a half of one volume at most, which is essentially nothing.
We could talk about the quality of a drama or some narrative decisions, but saying that it's not building characters is just dishonest. Because building characters doesn't necessarily mean "growth" or anything like that, their negatives are also parts of their personalities, and exploring that can be more interesting than the usual "overcoming their weaknesses" yada yada.
But many people get so mad at the very idea of a drama that they pretty much ignore what is being shown. For one, I agree with you that using the kid as a plot device to resolve the drama is pretty contrived. But most complaints do not address this kind of stuff, they usually just hate that there's a drama and it's ruining their vibes or something.
It's not about having drama in manga (ok, maybe for some people it is), it's the way this specific story is being told.
After the time skip, we had a whole bunch of new characters dumped on us without much supporting context in a series of rapid-fire short vignettes. The artistic style also got more complex, to the point where it's a struggle not only to distinguish the three brown-hair girls from each other, but at times also just figure out what's going on on the page. Both of those elements combined make it difficult to tell what's going on other than scattered bits and pieces.
Compare that to pre-timeskip where the art had better readability (even if it was less styled) and the pace didn't jump around so much, and it's been a big swerve in this second part.
Legitimately, I could use a summary of what's going on post-timeskip. I get that Mitsuki was in a band and it didn't work out, Mitsuki has some personal issues with her perception of herself and view of her relationship, Mitsuki and Aya aren't talking to each other, and Aki ran off because his "friends" look down upon his interests. But what about the other characters? Who are they and what is their involvement? Aya fell asleep on some college girl's shoulder at a drinking party and that caused Mitsuki's down-spiral? Did Mitsuki stop talking to Aya because she humiliated herself on stage in front of her lover? Even on reread I feel like I can only understand about 40% of the recent story. And without knowing the intricacies of what is behind Mitsuki's spiral, it's hard to empathize with her, and thus be immersed in the drama.
I don't think I'm alone in my confusion?