Two-factor authentication for Apple ID - Apple Support

Check your Apple ID device list to find where you're signed in - Apple Support

How to deal with Your Apple ID currently has two-step verification turned on, but two-factor authentication is required. on developer.apple.com? - Ask Different

Apple being sued because two-factor authentication on an iPhone or Mac takes too much time

How to Enable Two-Factor Authentication for Your Apple ID

Pro Tips: How To Use Apple Two-Factor Authentication

Cannot set up Apple Pay Cash because my Apple ID does not support two-factor authentication - but my iCloud devices are all ALREADY set up for 2FA using the very same AppleID

Get a verification code and sign in with two-factor authentication - Apple Support

Pro Tips: How To Use Apple Two-Factor Authentication

How to use Apple's Two-Factor Authentication to Secure your Personal Data

Can't find the 2FA option in my Apple ID … - Apple Community