Newspaper online account password is remembered on my Mac, but doesn't show in Keychain

MacBook Air mid-2013, macOS Big Sur 11.7.10, Safari 16.6.1 I have an online subscription to the San Francisco Chronicle newspaper. When I navigate to the newspaper's website (https://www.sfchronicle.com) , the site logs me in and provides access to the online paper. I assume this indicates that the password has been saved in Keychain. Keychain Access does not, however, show the Chronicle account. When I search Keychain Access for the account itself or for the password (I wrote the password down when I opened the account), neither appears. Why doesn't the account or password appear in Keychain Access? Is it stored somewhere else? Should I do anything about it?