https://monitor.firefox.com/breach-details/LuminPDF

https://www.zdnet.com/article/data-of-24-3-million-lumin-pdf-users-shared-on-hacking-forum/

It's possible you've used their services in google drive before.

Thank you.

But that doesn't answer the more important question. If you are using your Google Account as the sign-in for things like LuminPDF, then what? Do you need to change your main Google Account Password?

Hi jesse.ulrich, when you use your Google Account to log in on a site, the site does not receive your Google password, they receive a token which provides access to some of your Google account information, but not your password.

More info: https://support.google.com/accounts/answer/112802