Comment by latchkey
At least in my own experience, I tried building a relatively simple static SPA NextJS React app with their router, and wanted to host it on CloudFlare Pages.
It ran locally in dev mode just fine. Once I deployed it on CFP, the router broke. No errors in the console, it just didn't work.
If I'm forced to use Vercel to make a simple SPA work, which then forced me into paying for their service, that's the problem.
OpenNext on Cloudflare is the only way I've successfully gotten NextJS to work in a Cloudflare Worker.
https://opennext.js.org/cloudflare