Authenticator App
https://lemmy.one/post/182140
What authenticator app do you use? How do you backup? Any open source self hosted options?
A native, lightweight and secure one-time-password (OTP) client built for iOS; Raivo OTP! - History for LICENSE.md - raivo-otp/ios-application
I was going to mention this as well. I went from Google, to Authy, to Raivo OTP and never looked back. Their sync system is great too.
They have a website too with more articles as well https://raivo-otp.com/
A native, lightweight, non-commercial and secure multi-factor authenticator that synchronises your one-time passwords across all of your Apple devices.