Luckily I found out before it stopped working on my device and was able to still use Authy long enough to login and create new tokens stored in a different authenticator. I previously thought I'd be protected from issues with a single devide, since Authy will sync your tokens to multiple devices, except they also had recently stopped supporting their desktop software (my second device). This also meant that I couldn't easily export the existing tokens and had to spend a bunch of time logging into each account to create new TOTP authentication tokens.
Note also that I didn't find this out from Authy (as I should have if they were doing their job); I found it out from discussion on Mastodon in this thread
One saving grace here is that for really important things I use my Yubikey, FIDO2 (i.e. webauthn) if possible and failing that TOTP with the secret stored on the Yubikey, so if I had failed to switch authenticators before the Authy debacle at least I could still get into the important things. I also try to always download and store an encrypted copy of any backup codes, but not all services seem to provide them.
#2FA