Just eww... you were an expert at Rails 10+ years, failed to become an equivalent expert at Next.js so you went back to what you're used to. You just didn't dive in deep enough.
I was the same expert level with Python, now I'm using trpc, nextjs, drizzle, wakaq-ts, hosted on DO App Platform and you couldn't pay me enough to go back to Python, let alone the shitstorm mess that's every Rails app I've ever worked on.
I've also not seen the 1s Next.js pageloads you had, but I'm confident of figuring a fix if that becomes a problem.