what does it mean when there is an exclamation mark next an account in the settings > passwords and accounts

I forgot a password for one of my accounts, and I went onto my phone to see if <Passwords and Accounts> in settings had it stored. Thanks to Apple, it did. Although, when I went to the website that I wanted and typed the credentials, it said: "Accessed denied." I didn't notice it at first, but when I checked back at my UserN and Pass., I noticed a tiny triangle with an exclamation mark, and that was the only website that Apple's stored credentials are not valid. Can someone help?

P.S. When I submitted my post to the community, it said to chose a community to post to, but my question didn't pertain to a specific community, so sry if this question has nothing to do with your area of expertise. I just need help. Anything is good. 😉