Just heads up there’s a site on Google Privacy if you want to read deeper.
Your data privacy matters. Learn how Google keeps your personal information private and safe - and puts you in control.privacy.google.com
Also, Alexa is always listening to you as well.. so is Siri, as of iOS10, if you switch up your settings to allow hands free mode.
Think about it.. how else would Alexa pick up “Hey, Alexa” and Siri can pick up “Hey, Siri”.. they’re always listening. Google is just the most transparent about it, which is actually quite comforting IMO.