Google error 401 - The server cannot process the request because it is malformed. It should not be retried.

## Google 401 Malformed Request on Android when adding new account (Cognito + Google Sync)

### Description
I'm experiencing a **401 Malformed Request** error specifically on Android when using AWS Cognito as an Identity Provider with Google.

The issue occurs only when the device has Google account synchronization active and the user attempts to **add a new Google account** during the sign-in process.

### Steps to Reproduce
1. Trigger the login flow using `authorize` with Google/Cognito.
2. When the Google account selector appears, instead of picking an existing account, select **"Add another account"**.
3. Complete the Android system's native verification (fingerprint/PIN).
4. Enter the new account credentials.
5. The Android system displays a native "Terms and Conditions" / "Google Play Services" acceptance screen.
6. After accepting, instead of redirecting back to the app/Cognito, the browser displays a Google 401 error.

### Observations
* The issue **does not happen** if an existing account from the list is selected.
* The issue **does not happen on iOS**.
* Other providers (Microsoft, Apple) work perfectly.
* The redirected URL in the browser shows `authuser=unknown`, suggesting the session context is lost when the Android System Assistant takes over the UI focus.

### Error URL (Redacted)
`https://accounts.google.com/signin/oauth/consent?authuser=unknown&part=...&flowName=GeneralOAuthFlow&client_id=REDACTED.apps.googleusercontent.com&requestPath=%2Fsignin%2Foauth%2Fconsent#`

### Code Snippet
```javascript
const socialConfig = {
serviceConfiguration: {
authorizationEndpoint: `https://${COGNITO_URL}/oauth2/authorize`,
tokenEndpoint: `https://${COGNITO_URL}/oauth2/token`,
},
clientId: CLIENT_ID,
redirectUrl: REDIRECT_URL,
scopes: ['email', 'openid', 'profile'],
additionalParameters: {
identity_provider: 'Google',
prompt: 'select_account',
},
usePKCE: true,
};

const result = await authorize(socialConfig);
```

## Environment
* **Identity Provider**: `Cognito`
* **Platform experiencing the issue on**: `Android`
* **React Native Version**: `0.83.1`
* **react-native-app-auth Version**: `8.1.0`
* **Platform**: Android (tested on API 36)
* **Device**: Physical device with Google Sync active.

提供されている socialConfig と認可フローから始め、特に Cognito の認可エンドポイント、Google identity_provider、prompt の設定を確認します。Google Sync が有効な物理 Android API 36 デバイスで、「Add another account」を選択し、ネイティブの Google Play Services の規約に同意して再現します。フローが Google 401 malformed-request ページを表示するのではなく、アプリ/Cognito に戻れば完了です。

索引モデルが issue の本文から書いたものです。