How does Google identify that one of my saved passwords has been exposed by a data breach if they don’t know my password, and yet…my other Google account, which used that same password, did *not* force me to change it?

I’m tidying up my passwords, and as far as I understand if a hash matches, it’s confirmation of an input. So, does Chrome check the stored hashes of my password against that of the publicly available database it found?

The follow up question. I had also used that exposed password for a separate Google account but… if it was known that password was compromised, why did it let me use it when logging into my other account and make *no mention of it immediately upon login?*

All my passwords are complex and unique now, so last request if you will: your suggested cross platform password manager.

Thanks