Authenticate microsoft account to firebase website only, and not other microsoft services

I am using firebase for a website, where users can sign in with their microsoft accounts:

import {getAuth, signInWithRedirect, OAuthProvider} from "firebase/auth";

(...)

const provider = new OAuthProvider('microsoft.com');
const auth = getAuth();
signInWithRedirect(auth, provider);

I have managed to make everything work nicely, except one detail:
When I sign in with the Microsoft account in the webbrowser for the firebase site, I am also signed in to my complete Office 365 account in the background (and probably other mirosoft sites).

So if I go to the website for my Outlook 365 online mail, then I am already logged in since I logged into my firebase project.

How can I limit the microsoft sign-in to only authenticate in the firebase project, and nothing else?