I thought I will only give them my email address using Google login? I am appreciated if you can add more details. I am using my Google login everywhere and may not know the disadvantages.
We have this at my company at well. However, I treat it as a piece of paper, no more no less because the owner of my company has no intention to sale at all.
When I traveled away from my home, google always asked me for extra information such as phone number or secondary email verification. I found that's very useful and at time, very annoying. Not sure if i want to type in 2 passwords every time.