Summary

Code: FUNCTION_INVOCATION_TIMEOUT

I am using NextJS as frontend service and ExpressJS as backend service. I am using getServerSideProps for SSR in some of my pages. For the cors issue on production, I am setting proxy while calling the backend service.
So, I have configured next.config.mjs file like below

  async rewrites() {
    return [
      {
        source: "/api/:path*",
        destination: `${process.env.NEXT_PUBLIC_EXTERNAL_API}/:path*`,
      },
    ];
  },

I have deployed my nextjs app on vercel. It was running well a few days back. But now while hitting the page I am getting 504: GATEWAY_TIMEOUT, Code: FUNCTION_INVOCATION_TIMEOUT.

Note: I am not getting the above error in the pages where I am not using getServerSideProps.

Need some help on this!

Additional information

/** @type {import('next').NextConfig} */

const nextConfig = {
  reactStrictMode: true,
  images: {
    domains: ['test.s3.ap-south-1.amazonaws.com', 'via.placeholder.com'],
  },
  async redirects() {
    return [
      {
        source: '/',
        destination: '/upcoming',
        permanent: false
      },
    ]
  },
  async headers() {
    return [
      {
        source: '/(.*)', // Matches all routes
        headers: [
          {
            key: 'Access-Control-Allow-Credentials',
            value: 'true',
          },
          {
            key: 'Access-Control-Allow-Origin',
            value: '*', // You can also restrict this to specific origins
          },
          {
            key: 'Access-Control-Allow-Methods',
            value: 'GET,OPTIONS,PATCH,DELETE,POST,PUT',
          },
          {
            key: 'Access-Control-Allow-Headers',
            value: 'X-CSRF-Token, X-Requested-With, Accept, Accept-Version, Content-Length, Content-MD5, Content-Type, Date, X-Api-Version, Authorization',
          },
          {
            key: 'X-DNS-Prefetch-Control',
            value: 'on'
          },
          {
            key: 'X-Frame-Options',
            value: 'SAMEORIGIN'
          }
        ],
      },
    ];
  },
  async rewrites() {
    return [
      {
        source: "/api/:path*",
        destination: `${process.env.NEXT_PUBLIC_EXTERNAL_API}/:path*`,
      },
    ];
  },
}

export default nextConfig;

I tried Changing next.config.mjs configurations and it did not work.