Do you have Chrome save your passwords for sites like BYC?
My guess is that your Google account, Chrome Browser, etc. got hacked / compromised and they are telling you to update all the passwords on sites where you saved your password.
I'm not saying 100% that's what it is, but in the 15 years I've been doing this and seen dozens of "my account was hacked", it was never a BYC compromise.
Also, if BYC was compromised, we'd have hundreds and hundreds (thousands) of people lighting up this forum and our email box.