Use next rewrites for API_URL.

next.config.ts

@@ -123,6 +123,7 @@ if (isProd) {
 }
 
 const rewrites = [];
+const beforeFilesRewrites = [];
 
 if (trackerScriptURL) {
   rewrites.push({
@@ -157,6 +158,11 @@ if (isRelativeUrl(apiUrl)) {
       destination: '/api/:path*',
     });
   }
+} else if (apiUrl) {
+  beforeFilesRewrites.push({
+    source: '/api/:path((?!auth(?:/|$)|config(?:/|$)).*)',
+    destination: `${apiUrl.replace(/\/+$/, '')}/:path`,
+  });
 }
 
 const redirects = [
@@ -244,17 +250,20 @@ export default withNextIntl({
     return headers;
   },
   async rewrites() {
-    return [
-      ...rewrites,
-      {
-        source: '/telemetry.js',
-        destination: '/api/scripts/telemetry',
-      },
-      {
-        source: '/teams/:teamId/:path*',
-        destination: '/:path*',
-      },
-    ];
+    return {
+      beforeFiles: beforeFilesRewrites,
+      afterFiles: [
+        ...rewrites,
+        {
+          source: '/telemetry.js',
+          destination: '/api/scripts/telemetry',
+        },
+        {
+          source: '/teams/:teamId/:path*',
+          destination: '/:path*',
+        },
+      ],
+    };
   },
   async redirects() {
     return [...redirects];