Apple has introduced a new feature that warns users when their stored passwords have been compromised in data breaches. iOS 14 includes the Keychain password manager that allows users to save credentials and automatically fill them into login forms on sites and apps. With the release of iOS 14, Apple will now check your stored credentials against a list of known data breaches in order to make sure they are secure. The feature is also triggers when logging into sites with compromised credentials, which could also be accessed by attackers, according to BleepingComputer.
Source: https://www.bleepingcomputer.com/news/apple/hands-on-with-ios-14s-new-data-breach-notification-feature/