Data breaches happen and most people are unaware or do not check automatically/recurring ..
two pairs of shoes here:
Cross-checking of email-addresses for previous data breaches
Check passwords for occurrence in data breaches (this is anonymous, only the first 5 characters of the hash are send, HIBP server responds with all matches, then compare locally .. ) (https://haveibeenpwned.com/API/v3#PwnedPasswords)
Data breaches happen and most people are unaware or do not check automatically/recurring ..
two pairs of shoes here: