Apple has released an update for Macs running Big Sur relating to updating and restoring iPhones and iPads using Finder.
The update is called a "Device Support Update" and weighs in at approximately 200MB.
Rather than a fix, this update likely adds support for new devices such as the iPhone 13 and iPad mini.
Device Support Update for macOS Big Sur
To download and install this update head over to System Preferences > Software Update and check for the latest patches and updates.