We've worked on this stuff for years (this stuff being how to warn users about compromised passwords). You can go back to 2018 with our work with Troy Hunt on Pwned Passwords (https://blog.cloudflare.com/validating-leaked-passwords-with...), or our 2021 work on a privacy-preserving way of checking a password against a list of known compromised passwords (https://blog.cloudflare.com/privacy-preserving-compromised-c...).
We've worked on this stuff for years (this stuff being how to warn users about compromised passwords). You can go back to 2018 with our work with Troy Hunt on Pwned Passwords (https://blog.cloudflare.com/validating-leaked-passwords-with...), or our 2021 work on a privacy-preserving way of checking a password against a list of known compromised passwords (https://blog.cloudflare.com/privacy-preserving-compromised-c...).