Apple notes that this beta version of iOS should only be deployed on devices dedicated for iOS 16.3 beta software development.
The iOS 16.3 and macOS 13.2 betas have introduced hardware security key support for Apple ID. For users who opt in, Security Keys strengthens Apple's two-factor authentication by requiring a hardware security key as one of the two factors. This takes two-factor authentication even further, preventing even an advanced attacker from obtaining a user's second factor in a phishing scam.