Bugs are easy.... you just point out the bug and move on... design flaws are hard... it's hard to bring up the fact that while yes, your module solves this one immediate problem, it was written so rigidly that two sprints from now the whole thing will need to be re-written scratch. Or maybe you took a particular approach that seemed easy to implement, but it won't do async stuff properly and so it needs to be re-worked from the ground up. And I get you solved your immediate problem for your immediate task, but whoever works on this next is going to have to completely re-think the approach and that's not theoretical, that next week when we add more behavior.

You ever worked on a team a where someone would go write code in their own crazy way that wouldn't follow any sort of existing pattern or take advantage of existing tooling? So they spend like a week on a simple task because they re-wrote the strings.c because they didn't want to include it? Yeah, they get fired eventually, but they are the worst to write code reviews for, because you go into it just thinking WTH, why are they doing it this way, this entire approach is convoluted and error-prone and rigid and fragile and complicated.

If a super engineer has advice for me on how to deal with this stuff, I'm all ears. I usually just ignore it unless it directly impacts me and then go back and re-write it when we have to add on to it/make it interop with some more code/release it as an available API.