Redirect flow within iframe with allowRedirectInIframe flag

My application B is hosted inside an iframe of another application A. The user journey is that the user logs into the parent application A and then clicks on the navigation menu which loads my application B in an iframe. This application B is an Angular SPA and the backend is hosted on a different domain. I am trying use Bearer tokens in this application B after acquiring a session with the redirect flow. I am using the "allowRedirectInIframe" flag as well. however this does not work. B starts the redirect flow comes back and starts it all over again and fails with the following error

I can see some issues/docs where it explicitly says that redirect flow is not possible in iframes. for eg https://github.com/AzureAD/microsoft-authentication-library-for-js/issues/3759 https://github.com/AzureAD/microsof...lob/dev/lib/msal-browser/docs/iframe-usage.md

But the existence of the "allowRedirectInIframe" flag leads me to believe that this is outdated. Please correct me if i am wrong. Otherwise can you tell me what i am doing wrong? I have attached my msal config and app.module.ts file below.

MSAL Configuration

auth: {
clientId: 'xxxxxxxxxxxx',
authority: b2cPolicies.authorities.signUpSignIn.authority,
knownAuthorities: [b2cPolicies.authorityDomain],
redirectUri: https://my.redirect.uri,
postLogoutRedirectUri: '/logged-out'
},
cache: {
cacheLocation: BrowserCacheLocation.LocalStorage,
storeAuthStateInCookie: false
},
system: {
loggerOptions: {
logLevel: LogLevel.Error,
piiLoggingEnabled: false,
},
allowRedirectInIframe: true,
},


Relevant Code Snippets

// app.module.ts code
providers: [
ConfigService,
{provide: HTTP_INTERCEPTORS, useClass: RequestHeaderInterceptor, multi: true},
{provide: HTTP_INTERCEPTORS, useClass: ConfigServiceInterceptor, multi: true, deps: [ConfigService]},
{provide: HTTP_INTERCEPTORS, useClass: RequestErrorInterceptor, multi: true, deps: [ToastrService]},
{provide: ErrorHandler, useClass: AppErrorHandler},
{
provide: HTTP_INTERCEPTORS,
useClass: MsalInterceptor,
multi: true,
},
{
provide: MSAL_INSTANCE,
useFactory: MSALInstanceFactory,
},
{
provide: MSAL_GUARD_CONFIG,
useFactory: MSALGuardConfigFactory,
},
{
provide: MSAL_INTERCEPTOR_CONFIG,
useFactory: MSALInterceptorConfigFactory,
},
MsalService,
MsalGuard,
MsalBroadcastService,
// {
// provide: APP_INITIALIZER,
// multi: true,
// deps: [MsalService],
// useFactory: (authService: MsalService) => {
// return () => {
// return authService.ssoSilent({
// scopes: []
// }).toPromise();
// };
// }
// },
],
bootstrap: [AppComponent]
})


Core Library MSAL.js v2 (@azure/msal-browser)

Core Library Version 2.22.0

Wrapper Library MSAL Angular (@azure/msal-angular)

Wrapper Library Version 2.1.1

Identity Provider : Azure B2C Custom Policy Source : External (Customer)

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