Why is 'Restore Backup' greyed out for an iPhone 12 backup on iTunes PC?

Im on PC. I moved my iPhone Backup I made two months ago to an external harddrive and back again (into the same folder) recently after my old phone broke. Now I want to restore from that backup. My new phone is an iPhone X with iOS 16 (latest version for that model). The Backup has iOS 18.

The Backup is shown in the list of backups at Edit > Preferences > Devices, but on the main page of iTunes (image included) under Latest Backups it isn't showing up and the Restore button is greyed out.

I tried a lot already. Its the only way I can get the images and contacts from that old phone.

[Re-Titled by Moderator]