iTunes Library.itl cannot be read because it was created by a newer version of iTunes - need help!

Hi: My Windows 11 Pro 21H2 Dell Optiplex / iTunes / iPhone 8s Plus combo has suddenly gone unstable. It started when iTunes woke up and decided it was going to back the the iPhone up to the PC, not to the cloud as it's always done. I kept checking the iCloud backup dot and "Applying" but it kept resetting itself to backing up to the PC? I made sure that I was logged into the Store and iCloud etc., but iTunes was simply rejecting input from the PC. Then the phone started asking me if I trusted the PC and asking for a password every time I tried to sync. The phone and PC otherwise seem to be working fine, so I tried a "Repair" on iTunes from the Windows control panel - no luck. Then I uninstalled iTunes and reinstalled the latest version, and I got the following error much to my surprise "The file iTunes Library.itl cannot be read because it was created by a newer version of iTunes." This makes no sense - I downloaded the latest version of iTunes both directly from Apple and from the Microsoft store. I searched for a solution to the problem and I've tried both the approaches I found. I renamed the current .itl file as .old, moved it out of the folder, found the newest old version of the itl file in the previous version folder, copied and pasted this to the top level and renamed it .itl. Same error. I tried several different previous versions? Then I deleted the .itl file in the iTunes library folder in Music and restarted the program without one as I was informed that the program would create one if it didn't find one. Nope - same error. What's weird is that the last time iTunes created a new .itl file was 2.5 years ago? I tried installing older versions of iTunes - I have installer files going back to 2016 - same error?? Anyone have any ideas? Thanks, John