The data wasn’t manually entered manually by me or anyone using my account, but yet the data is associated with my account? How did that happen?
My first step was to hit that little “Manage…” button Google has deprioritized at the bottom of their credential window to see where it took me. What I found out is that Google, as expected, has been keeping track of me very well. Upon arrival to the controls page, I found a list of “Saved Passwords” (duh) as well as a list of “Never Saved” passwords.