CloudKit sign in error in normal tab

Hi,

I'm trying to sign in with Apple CloudKit.

I'm using the following code:

'use client';

import { CLOUDKIT_CONSTANTS } from '@/constants/cloudkit';
import { setCloudKitConfigured } from '@/lib/cloudkitSingleton';
import { CloudKitStatic } from '@/types/cloudkit';
import Script from 'next/script';

declare global {
  interface Window {
    CloudKit: CloudKitStatic;
  }
}

export default function Home() {
  const initializeCloudKit = async () => {
    console.info('⭐️ initializeCloudKit - start');

    // 古い認証情報を削除
    try {
      // LocalStorageから古い認証情報を削除
      const keysToRemove = [];
      for (let i = 0; i < localStorage.length; i++) {
        const key = localStorage.key(i);
        if (key && (key.includes('cloudkit') || key.includes('CloudKit'))) {
          keysToRemove.push(key);
        }
      }
      keysToRemove.forEach(key => localStorage.removeItem(key));

      // SessionStorageからも削除
      const sessionKeysToRemove = [];
      for (let i = 0; i < sessionStorage.length; i++) {
        const key = sessionStorage.key(i);
        if (key && (key.includes('cloudkit') || key.includes('CloudKit'))) {
          sessionKeysToRemove.push(key);
        }
      }
      sessionKeysToRemove.forEach(key => sessionStorage.removeItem(key));

      console.log('古い認証情報を削除しました');
    } catch (cleanupError) {
      console.warn('認証情報のクリーンアップ中にエラー:', cleanupError);
    }

    try {
      const cloudKit = window.CloudKit.configure({
        containers: [
          {
            containerIdentifier: 'XXXXXX',
            apiTokenAuth: {
              apiToken: 'XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX',
              persist: false,
              signInButton: {
                id: 'cloudkit-sign-in-button',
                theme: 'black',
              },
              signOutButton: {
                id: 'cloudkit-sign-out-button',
                theme: 'black',
              },
            },
            environment: 'development',
          },
        ],
      });
      console.info('⭐️ cloudKit', cloudKit);

      setCloudKitConfigured(true);

      const container = cloudKit.getDefaultContainer();

      console.info('⭐️ CloudKit configured, setting up auth...');

      // 初期認証状態をチェック
      try {
        const initialUser = await container.setUpAuth();
        console.info('⭐️ setUpAuth result:', initialUser);
      } catch (authError) {
        console.info('⭐️ setUpAuth error (expected for unauthenticated):', authError);
      }

      // CloudKitの標準コールバックも併用（念のため）
      try {
        container.whenUserSignsIn().then((userInfo: any) => {
          console.info('⭐️ CALLBACK: whenUserSignsIn fired!', userInfo);
        });

        container.whenUserSignsOut().then(() => {
          console.info('⭐️ CALLBACK: whenUserSignsOut fired!');
        });
      } catch (callbackError) {
        console.info('⭐️ Callback setup error (non-critical):', callbackError);
      }

      console.info('⭐️ initializeCloudKit - completed');
    } catch (error) {
      console.error('⭐️ Critical CloudKit initialization error:', error);
    }
  };

  return (
    <>
      <Script
        src="https://cdn.apple-cloudkit.com/ck/2/cloudkit.js"
        strategy="afterInteractive"
        onLoad={() => {
          initializeCloudKit();
        }}
        onError={error => {
          console.error('⭐️ CloudKit initialization error:', error);
        }}
      />
      <div id="cloudkit-sign-in-button" />
      <div id="cloudkit-sign-out-button" />
    </>
  );
}

In Chrome secret tab, I can sign in successfully. But in Chrome normal tab, I can't sign in.

In normal tab, following error occurs on sign in button click:

cloudkit.js:14 Uncaught (in promise) Error: UNKNOWN_ERROR
cloudkit.js:14  GET https://api.apple-cloudkit.com/database/1/XXXXXX/XXXXXX/public/users/caller?ckjsBuildVersion=2420ProjectDev22&ckjsVersion=2.6.4&clientId=XXXXX-XXXXXXX-XXXX-XXXXX&
ckAPIToken=XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX 
421 (Misdirected Request)

I think, cloudkit instance has re-initialized when I click the sign in button only in normal tab. So I can't sign in.

Do you have any idea what might be causing the error ?

Thanks in advance for your help!