You're right as hell and to be frank this has got be the worse case I've come across thus far. Although the story ends on a calm, happy note the story feels WAY too short, and not in a sense of it was so good I wish it wasn't over, but rather in a where's the rest something is missing sense. What once was a interesting premise with a decent plot is now an incomplete story that lacks substance. Like wtf the fact that I can say with exceptional confidence that I've read all sorts of one shots that where more fleshed out than this is crazy especially because this really really didn't need to be short and had more than enough potential to be a full length story. Honestly, even if the author would have preferred something short they could have added a few more chapters to flesh the story out a bit and that would have worked just fine, but instead we got something that feels like they wanted to get paid so they just put something out, they had to fill a quota, or something. I don't know and I'm not sure I care ughh.
I hate it when a story "ends" but then has side stories that are really just the ACTUAL end of the main story. Like this one, chapter 4 is not the end with 2 side stories, this story is 6 chapters. I've just seen multiple authors do this now where they claim it's the end but nothing has actually been solved and then they use the side stories to clean everything up. That's not what side stories are for!!
God sorry it's just been something I've noticed more and more lately and it's just gotten annoying