I think I may have unintentionally done something wrong on my laptop.
I am using a Windows 10 laptop and had iTunes version 18.104.22.168 installed.
I was updating my old iPhone 6s from iOS 9 to iOS 15. I thought everything was going smoothly when it displayed an error saying iTunes could not update the device unknown error (4). I thought it might be the iTunes version, so I installed the latest version and it updated the iPhone to iOS 15.
But I noticed that I could no longer see the apps which I had on my PC. So, I uninstalled the new version of iTunes and reinstalled version 22.214.171.124. But then it could not find the iTunes Library.itl file. After some reading around, I found a recent version (it had many versions) of it in the Previous iTunes Libraries.
But now I cannot see the backups in iTunes > Edit > Preferences > Device Backups. I can see them in the MobileSync folder, but not via iTunes.
I was going to uninstall iTunes 100% and back up the MobileSync folder and the iTunes Media folder which has all the voice memos, etc., and reinstall version 126.96.36.199 to see if this works.
But I was hoping someone could shed some light on this, maybe there is a workaround for this.