The most common solution is one-time-use backup codes that most services give you when enrolling. Hopefully you saved them somewhere safe!

The main issue is Google Authenticator and how popular it is. As GP noticed, it doesn't flag the files as being allowed for backup which is kind of ridiculous. Almost anything is better, https://getaegis.app/ is my recommendation.

You can also manually backup your seed (screenshot / save the QR code during enrollment).

I think the only way to handle the possibility of failure of a 2FA system is to have multiple options configured. They all can fail somehow: loss, damage, hardware failure, etc. On my Google account I have two security keys, an OTP app, and saved backup codes.

That's not user friendly though. I don't see how to make a user friendly, reliable, and safe 2FA system. Not having 2FA isn't safe either!

Yeah, I've been burned by Goog Authenticator not being cloud. I use 1pass for 2FA now and it works in the cloud at least.