Yeah, that's what I meant if I don't back up the seed for the authenticator. Thanks for the information, I'll check the alternatives to Google 2FA
Please help me with my question concerning 2FA. Do you think it's essential security measure, does it work very well? Then Google will have my security code, right?
I'm just afraid to do smth wrong like lose password or QR-code or smth and lose my crypto.
No, Google should not have your security code. Actually if you lose your phone and didn't back up properly the seed for the authenticator (when you created/set up the 2FA) you'll probably lose it.
This being said there are better alternatives than Google Authenticator, which do the same job but also allows you keep a safe copy somewhere.
It works well, but you may have surprises in the future, because the generated code is based on timestamp. And if your phone, the auth app or the website where you try to enter don't have the time set well, the code will not be accepted. (Usually a sync of your phone fixes this).
About losing crypto. If you use the 2FA on the same phone as you access the web services, you weaken the security by a great deal and if the phone is lost, stolen or compromised you may lose funds also with 2FA.
Imho the main rule is to keep the funds you don't need "now" safely offline on a wallet you and only you control. This means no web wallet, no big money on exchanges, no cloud, desktop or e-mail backup of the seed/private keys (use paper, steel, whatever). And/or make use of hardware wallet.