Useless anecdote: I don't have direct experience with Next.js[1] (but React, Angular, Vue, Solid), but I did help a co-worker out with something in their Next.js app, and as soon as I saw the madness that was file-based routing I wrote off the whole thing.
[1]: mostly because I have never been interested in the modern form of SSR due to my controversial belief that that is a truly _insane_ solution to SEO, TTFB and page load performance. You don't really solve a problem by piling more problems on top, however many billion man-hours a whole industry spends on that endeavor.