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Authy got hacked, and 33 million user phone numbers were stolen
(appleinsider.com)
This is a most excellent place for technology news and articles.
It's completely optional to connect a Google account. You can always back them up using the QR code (just take a picture with another device)
Protip: Don't do any of this, unless you hate your accounts being secure.
An encrypted backup, and a stash of recovery codes for important accounts is the most secure way.