I agree with the comments about side couples feeling like random doujins rather than part of a cohesive story. Either commit to one-shots or commit to a central narrative, and don't constantly interrupt the latter for the former.
I'd be interested in hearing what others see as specifically changing in the drawing style.
I just reread the older chapters to give you a more detailed explanation of my thoughts, and I think it's less about the individual elements used in isolation, and more about how universally they're applied? Like, everything feels way more "shiny" and "moe" now, from the colours to the style.
imo, that feeling is strongest in how the eyes are drawn now. They have, like, 50 light circles in them at all points, instead of just for emotive effect, and the shading for them feels softer and lighter, with greys rather than blacks, even for characters who used to have exclusively black eyes. They're also substantially larger, with the pupils often not even touching what's supposed to be the upper lid, and they're contorting with the brows less.
Yeah, idk. Everyone just feels a whole lot less expressive in general because of the changes.