我经历过这个确切的问题-不清楚原因，但我发现，如果我直接从firebase库导入方法，我可以解决它们。
具体来说，我导入这些功能如下：

import { browserLocalPersistence,browserSessionPersistence, setPersistence } from 'firebase/auth';

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而不是从'@angular/fire/auth'
然后它就完美地工作了（就像在一个普通的JavaScript应用程序中一样）。

从persisting auth state persistence in the JavaScript/web SDK的文档中：
对于Web应用程序，默认行为是即使在用户关闭浏览器之后也保持用户的会话。
我强烈建议只有在你知道你有一个特定的用例需要它的时候才调用setPersistence。在大多数浏览器上，Firebase已经在重新加载之间持久化了auth状态，而不调用setPersistence。

我已经离开了我的实现登录与供应商下面。
虽然我在这个项目中还没有迁移到Modular Firebase V9，但身份验证持久化仍然可以正常工作--登录过一次的用户不需要每次回来都重新登录。
我发现在服务中保留认证逻辑是一个很好的做法，可以将其注入到组件或模块中。
在构造器中，您可以找到一种很好的方法来确定您的用户是否已登录，并且在Cloud Firestore中具有与其auth ID相关联的配置文件。

export class AuthService {

  analytics = firebase.analytics(); // this declaration works better than constructor init from import
  userCredential; // to store the promise returned when signing up/ in with email & password
  // type: User from the model
  user$: Observable<User>; // defined as observable as it can change when user signs in/out

  constructor(
    // inject imports for fire store auth service in constructor
    private afAuth: AngularFireAuth,
    private afs: AngularFirestore,
    private router: Router
  ) {

    // Get the auth state, then fetch the Firestore user document or return null
    this.user$ = this.afAuth.authState.pipe(  // define the observable state
      switchMap(user => {
        // Logged in
        if (user) { // if user is defined
          // point to document with matching ID
          return this.afs.doc<User>(`users/${user.uid}`).valueChanges();
        } else {
          // Logged out
          return of(null); // allows us to tell when user is not logged in
        }
      })
    );
  }

  /**
   * Authenticate users with Google O-Auth provider
   * @param {boolean=} [registration = false] - whether this is the first sign in or not
   */
  async googleSignIn(registration: boolean = false) {

    // reference google auth provider
    const provider = new auth.GoogleAuthProvider();
    // pass provider to sign in with popup functionality
    this.userCredential = await this.afAuth.signInWithPopup(provider);

    if (registration) { // if the request is coming from the registration page

      try {
        await this.insertNewUser(this.userCredential.user, this.userCredential.user.displayName);
        await this.verifyEmail(); // send a verification email to the user when registering
        await this.router.navigate(['/user-profile']);
      } catch (err) {
        console.log(`Error: ${err.errorMessage}`);
        M.toast({html: `Error: ${err.errorMessage}`, classes: 'rounded materialize-red'});
      }

    } else {  //  user is logging in again

      try {
        await this.router.navigate(['/user-profile']);
        M.toast({html: `Signed in as ${this.userCredential.user.displayName}`, classes: 'rounded blue'});

        // let user know that they haven't been verified
        if (!this.userCredential.emailVerified) {
          console.log(`user's email has not been verified`);
          M.toast({
            html: `Your email has not yet been verified. Please check your inbox.`,
            classes: 'rounded orange darken-2'
          });
        }

      } catch (err) {
        console.log(`Error: ${err.errorMessage}`);
        M.toast({html: `Error: ${err.errorMessage}`, classes: 'rounded materialize-red'});
      }

    }

    // track the login event with analytics
    this.analytics.logEvent('login', {serviceName: 'Google Login'});

  } // end of sign in function

} // end of auth service

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