Thank you kindly for your reply, and for sharing more info.
Re: " ... It's as if this userid and password never existed, but it is one I use almost every day,..."
✽ Apple advises: Archive or make copies of the information you store in iCloud - Apple Support although, does not mention passwords.
✽ You may want to check whether that crucial account's website is allowed access to your password. For MacOS 26: Allow apps to access your keychain - Apple Support
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Re: "If the Passwords were not an icloud program I could have restored from backup, ..." " ... only validates my wanting redundancy for saving passwords ..."
✽ Export passwords to another password manager on iPhone - Apple Support
says:
"You can export your passwords for websites and accounts to a CSV file ... "
(Gives a warning that the passwords are not encrypted.)
✽ We can also:
Export Safari data to another browser in Safari on Mac - Apple Support
✽ Some folks keep a small A-Z notebook on hand, where they keep up-to-date passwords. However, unless locked away safely, this also leaves the possibility of mis-use. Very handy though, if our own devices are somehow not available to us.
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Re: "I was curious to see if this had happened to anyone else and to maybe alert the Apple techs to a possible glich out there".
As Apple users, like yourself, we have no access to feedback sent to Apple.
Seems there are isolated cases from time to time. Causes may vary considerably.
A few examples below from searching through earlier threads in the community:
✽ Passwords in system settings has disappeared: https://discussions.apple.com/thread/255876064
✽ My passwords have disappeared from System… - Apple Community
✽ Missing passwords on both Mac and iPhone after upgrading to iOS 18
https://discussions.apple.com/thread/255865571
✽ If needed: Apple's feedback website: Product Feedback - Apple