chore(backend): Warn about __unstable_options deprecation

packages/backend/src/index.ts

@@ -1,3 +1,5 @@
+import { deprecatedObjectProperty } from '@clerk/shared';
+
 import type { CreateBackendApiOptions } from './api';
 import { createBackendApiClient } from './api';
 import type { CreateAuthenticateRequestOptions } from './tokens';
@@ -26,12 +28,22 @@ export function Clerk(options: ClerkOptions) {
   const apiClient = createBackendApiClient(opts);
   const requestState = createAuthenticateRequest({ options: opts, apiClient });
 
-  return {
+  const clerkInstance = {
     ...apiClient,
     ...requestState,
     /**
      * @deprecated This prop has been deprecated and will be removed in the next major release.
      */
     __unstable_options: opts,
   };
+
+  // The __unstable_options is not being used internally and
+  // it's only being set in packages/sdk-node/src/clerkClient.ts#L86
+  deprecatedObjectProperty(
+    clerkInstance,
+    '__unstable_options',
+    'Use `createClerkClient({...})` to create a new clerk instance instead.',
+  );
+
+  return clerkInstance;
 }