[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.

Beginne mit dem im Issue beschriebenen minimalen AngularFire-Authentifizierungssetup und verwende den canActivate-Guard mit redirectLoggedInTo und redirectUnauthorizedTo. Reproduziere das Verhalten mit zwei Tabs, leere in einem den Cache und aktualisiere ihn. Fertig ist es, wenn der aktualisierte Tab normal geladen wird, anstatt einen leeren Bildschirm anzuzeigen, während der andere Tab geöffnet bleibt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.