Confirmed that the support article has been removed. Most Keychain problems are when you change your Mac password and are not being flooded by many prompts to unlock the keychain. The Keychain utilizes an encrypted storage and is locked with the previous password. When you login, your Mac password attempts to unlock the keychain to make it available. Since changing a Mac password the keychain cannot be unlocked. The prompts provided by Apple are shall we say, unsatisfactory in explaining what has occurred. You need to enter the previous password to unlock the keychain. If you do not know the previous password you will have to reset the keychain. You can do that by opening the Keychain Access app in /Applications/Utilities (after you clear all the Keychain pop-up prompts) and go to the Preferences in Keychain Access and click the "Reset Default Keychains..." button. This will move the original keychain out of the way and create new login and iCloud Keychain then if you have sync'ing your keychain to iCloud all your saved logins should resync. There is the potential loss of data but you can then add the moved keychain to Keychain Access and attempt to unlock it with the correct password. There is no way to reset a keychain password.
Here's the Keychain Users Guide and there's a trouble-shooting section under the Table of Contents link:
https://support.apple.com/guide/keychain-access/welcome/mac