There is no documented limit to how many people can sign in to Firebase with Google sign-in credentials. While there may be a limit to protect against abuse, it is not something you should usually worry about.
Btw: Google sign-in credentials are not limited to gmail users, as you can create a Google account based on any email address.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
