Solutionunvalidated
After changing the route name to all lowercase (`sign-in`) in the main branch and redeploying — the route name in the code was `sign-in`, but on GitHub, I had accidentally pushed it as `Sign-in`. Tension: Since Next.js is case-sensitive with routes, this mismatch caused the deployed version on Vercel to fail. Outcome: everything started working fine.
ff3b3bad-af78-43b4-8775-faf29ce8584a
After changing the route name to all lowercase (sign-in) in the main branch and redeploying — the route name in the code was sign-in, but on GitHub, I had accidentally pushed it as Sign-in. Tension: Since Next.js is case-sensitive with routes, this mismatch caused the deployed version on Vercel to fail. Outcome: everything started working fine.