[Auth Guard - BUG] canActivate auth guard causes blank screen after cache clear with multiple tabs opens.

If using the canActivate auth guard (with spread syntax), If you have more than 1 tab open of the same app, and then you clear the cache by using the browser in one of the tabs, and try to refresh, it causes a blank screen, which resolves after you close the other open tab.

steps to reproduce:

versions:
"@angular/common": "^20.3.0",
"@angular/compiler": "^20.3.0",
"@angular/core": "^20.3.0",
"@angular/fire": "^20.0.1",
"@angular/forms": "^20.3.0",
"@angular/platform-browser": "^20.3.0",
"@angular/router": "^20.3.0",
"rxjs": "~7.8.0",
"tslib": "^2.3.0",
"zone.js": "~0.15.0"

steps to reproduce:
1. Create new project
2. install angular fire
3. setup authentication and firebase project
4. utilize the ...canActivate auth guard like below.
5. open two tabs of the same page.
6. in one of them, clear the cache (by using the button close to the url in chrome for ex)
7. refresh
8. blank screen.
9. verify that if you close the second tab, then the first one loads correctly.

```TS
const redirectTeste1 = () => redirectLoggedInTo('test2');
const redirectTeste2 = () => redirectUnauthorizedTo('teste1');

export const routes: Routes = [
{ path: '', redirectTo: 'teste1', pathMatch: 'full' },

{
path: 'teste1',
component: Test1,
...canActivate(redirectTeste1),
},

{
path: 'teste2',
component: Test2,
...canActivate(redirectTeste2),
},
];
```

lmk if this is somehow a user error, but with such a barebones configuration I think is a legitimate bug.

issue に記載されている最小限の AngularFire 認証セットアップから始め、redirectLoggedInTo と redirectUnauthorizedTo を指定した canActivate ガードを使用します。2 つのタブで動作を再現し、一方のタブでキャッシュをクリアして、そのタブをリフレッシュします。もう一方のタブを開いたまま、リフレッシュしたタブが空白画面を表示せず正常に読み込まれれば完了です。

索引モデルが issue の本文から書いたものです。