I'm seeing a possibly related issue, our Cognito Pre Token Generation lambda function was triggered 82 times in less than a second for the same user.

I see this issue too..specially on android when using social federated sign up

Since i had business logic that was being called many times my workaround was to move the business logic out from Hub.listen and add another middle layer where my business logic gets executed. Sign in event in Hub.listen would redirect the user to the middle layer where my business logic gets executed and which then redirects to the appropriate screen.

I also have the same problem. The sign event is called multiple time when login

The code is quite simple

    Hub.listen("auth", ({ payload: { event, data } }) => {
      console.log('event', event)
      switch (event) {
        case "signIn":
          // console.log(123)
          this.setState({ user: data });
          break;
        case "signOut":
          this.setState({ user: null });
          break;
        case "customOAuthState":
          this.setState({ customState: data });
      }
    });