Fix

loaders/fumadocs-mdx-loader.cjs

@@ -0,0 +1,21 @@
+let esmLoader;
+
+module.exports = async function (source) {
+  if (!esmLoader) {
+    const mod = await import(
+      require('path').resolve(
+        __dirname,
+        '../node_modules/fumadocs-mdx/dist/webpack/mdx.js'
+      )
+    );
+    esmLoader = mod.default;
+  }
+
+  return new Promise((resolve, reject) => {
+    this.async = () => (err, result) => {
+      if (err) reject(err);
+      else resolve(result);
+    };
+    esmLoader.call(this, source);
+  });
+};

loaders/fumadocs-meta-loader.cjs

@@ -0,0 +1,21 @@
+let esmLoader;
+
+module.exports = async function (source) {
+  if (!esmLoader) {
+    const mod = await import(
+      require('path').resolve(
+        __dirname,
+        '../node_modules/fumadocs-mdx/dist/webpack/meta.js'
+      )
+    );
+    esmLoader = mod.default;
+  }
+
+  return new Promise((resolve, reject) => {
+    this.async = () => (err, result) => {
+      if (err) reject(err);
+      else resolve(result);
+    };
+    esmLoader.call(this, source);
+  });
+};