Can Deactivate guard runs only once in Angular

Yes I know it is a duplicate issue but previous post does not solve it.
Guard code:

duplicate issue

canDeactivate(component: ExamEndedComponent,
currentRoute: ActivatedRouteSnapshot, currentState: RouterStateSnapshot): Observable<boolean> | Promise<boolean> | boolean {
return this.store.select(fromRoot.getExamStatus)
.pipe(
take(1),
map((res: string) => {
console.log(res);
if (res === 'started') {
alert('stop');
console.log(currentState.url);
return false;
}
return true;
})
);
}


but the problem is when clicking on back button of browser the guard executes only once so when clicking again user can actually navigate away .
Also checked the issue in angular : https://github.com/angular/angular/issues/12851
but it tries to solve the issue by navigating again to the current route before return false like below :

back button

clicking again

canDeactivate(component: ExamEndedComponent,
currentRoute: ActivatedRouteSnapshot, currentState: RouterStateSnapshot): Observable<boolean> | Promise<boolean> | boolean {
return this.store.select(fromRoot.getExamStatus)
.pipe(
take(1),
map((res: string) => {
console.log(res);
if (res === 'started') {
alert('Deactivation blocked');
console.log(currentState.url);
this.router.navigate([currentState.url]);
return false;
}
return true;
})
);
}


At this point alert is called twice because before returning false I navigate to currentState so angular runs candeactivate again but after clicking again at back button the canDeactivate is not called.
Routing table :

const appRoutes: Routes = [
{ path: 'Authentication', component: AuthComponent},
{path: '', redirectTo: 'home', pathMatch: 'full'},
{ path: 'home', component: HomeComponent, children: [
{path: '', redirectTo: 'exam', pathMatch: 'full'},
{path: 'exam', component: ExamComponent, children: [
{path: '', redirectTo: 'start', pathMatch: 'full'},
{path: 'start', component: ExamStartComponent},
{path: 'started', component: ExamQuestionsComponent,
canActivate: [ExamQuestionsGuard],
canDeactivate: [ExamStartedDeactivateGuard]},
{path: 'ended', component: ExamEndedComponent, canDeactivate: [ExamStartedDeactivateGuard]}
], resolve: {exam: ExamResolver}}
],
canActivate: [AuthGuard], resolve: {sign: SignInResolver}}
];


What is the problem ? Thanks in advance .

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