I 100% agree. I've ran into the same issues, and I would never use Next.js for anything, and I will encourage every team at work to use something else. In general Next.js has so many layers of abstraction that 99.9999% of projects don't need. And the ones that do are probably better off building a bespoke solution from lower level parts. Next.js is easily the worst technology I've ever used.
Framework-defined infrastructure is a seriously cool and interesting idea, but nowadays Next feels more like an Infrastructure-defined framework; the Vercel platform's architecture and design are why things in Next are the way they are. It was supposed to be "Vercel adapts to Next", but instead we got four different kinds of subtly different function runtimes. My usage dashboard says my two most-used things are "Fluid Active CPU" and "ISR Writes". I just pay them $20/mo and pray none of those usages go over 100% because I wouldn't have the first clue why I'm going over if it does.
Half the labels on there are Star Trek technobabel, which I would take the effort of learning, except I'm convinced they're all going to change with the next major release anyway. Partly because, I keep hoping & praying they will. I know a concerning number of former die-hard Zeit fans who've taken their projects and customers elsewhere. At the end of the day, if they were to ask me what they need to address in the next major release, I seriously do not know how to answer that question beside "practically every major and minor decision y'all have made since and including the App Router was the wrong one". How do you recover from that? Idk.