If I am using dynamic routes, could they cause the 'failed to collect page data for /not-found' error? How can I resolve it?

Yes, incorrect handling of dynamic routes can lead to this. Ensure your dynamic route configurations are correctly set up and that your 404 page handles cases where dynamic paths don't exist. You may need to configure Vercel's rewrites or redirects to correctly route unmatched requests to your 404 page, or to use fallback static generation within the dynamic routes.