It’s because the mangaka of this is sick so I think to at least meet the monthly deadlines she decreased in the quality
That's a weird answer. From what I understand publishing companies and mangaka themselves hire assistants and trainees. Those assistants can take care of backgrounds, betas, shading, etc. Of course the more famous your manga is, the more resources you have available (like Eiichiro Oda has a couple of assistants that help with One Piece). But I would think that given how big Skip Beat is in the shoujo community Nakamura would receive the support to have enough people to draw backgrounds at the very least simple ones with no fancy shading.
If you buy the books there's more detail.
I see. So this is not the brushed up version. I find it weird that they don't do the assistant tasks before the magazine release (maybe I'm more used to how it's done with other authors). But makes sense if that's the reason.
They don't even bother drawing backgrounds anymore (and for a while now too). I've seen weekly manga with more detail. There's really no excuse for a monthly shoujo classic.