What is the things I can do to prevent the lost of my access ? Can I save a key/Qrcode and use it to get back my account ?
I would recommend replacing Google Authenticator with other open source 2FA apps like
Aegis,
andOTP that is available even for older Android smartphones with F-Droid, or
WinAuth for Windows OS.
You can then scan secret key QR codes with those apps (it would be a good idea to write them on paper also) and import them one by one, and make encrypted backup from settings after that.