Uhhhh, did you not read any of the last chapter? The author literally outlines the plotlines they were planning on doing but couldn't. Most likely the publisher just dropped the series and the author had x amount of chapters to wrap it up.
Hmm. I like the initial idea of an isekai character knowing what's going on, and ending up interacting with the big baddy or whatever, but wow this setup is contrived.
They could have just left it at 'MC takes brothers place to avoid plot point x' but instead there's a runaway mom with a debt...