it says it is encrypted but it is encrypred using keys that google has access to as they are unlocked with you logging in into google account.

First it uses lock screen password, so google do not have access to this password.

Even if your lock screen is unfortunately your Google password, I think proper authentication protocol do not send your password to Google to authenticate, but only the hash, which cannot be reverted to derive your password.

Obviously, the above is assuming that Google is not malicious. Otherwise it can just use play service, which is privileged and closed source, to get all your data. If your threat model including Google itself trying to steal your key, you will probably need to install a trusted rom or use iOS (however, apple and the rom developer can also steal your key).