As per this you can use the prompt querystring to tell google oauth that you'd like the user to choose the user account.
Can someone tell me how to do this in asp.net core - if you're using the AddGoogle code as per:
.AddGoogle(GoogleDefaults.AuthenticationScheme, googleOptions =>
{
googleOptions.ClientId = "***";
googleOptions.ClientSecret = "***";
googleOptions.AccessType = "offline";
googleOptions.UserInformationEndpoint = "https://www.googleapis.com/oauth2/v2/userinfo";
googleOptions.ClaimActions.Clear();
googleOptions.ClaimActions.MapJsonKey(ClaimTypes.NameIdentifier, "id");
googleOptions.ClaimActions.MapJsonKey(ClaimTypes.Name, "name");
googleOptions.ClaimActions.MapJsonKey(ClaimTypes.GivenName, "given_name");
googleOptions.ClaimActions.MapJsonKey(ClaimTypes.Surname, "family_name");
googleOptions.ClaimActions.MapJsonKey("urn:google:profile", "link");
googleOptions.ClaimActions.MapJsonKey(ClaimTypes.Email, "email");
})