Some apps and websites offer you the option of logging in to them using SSO (single sign-on) with accounts from other companies or groups. The login screen will then say, for example: "Login with Google" or "Login with Microsoft".
This is intended to increase convenience because you don't need to register separately. Unfortunately, this procedure has some disadvantages.
If your main password for an SSO provider is compromised, all other apps and websites that you use to log in will also be affected. This can also be a problem in cases of stalking or toxic relationships if one person is able to control several apps.
In addition, the providers of such logins collect detailed data about the use of the apps and websites in the background and theoretically have full access to your connected accounts.
This enables even more detailed profiling for data traders and advertising networks.