After the restart, Windows will create a backup of the registry in the RegBack folder and create a RegIdleBackup task to manage it Microsoft Learn Alternative Recovery Methods
Never manually copy from C:\Windows\System32\config\RegBack while Windows is running. Instead, always use reg save to export live hives, or boot into WinRE to manipulate the actual files.
Microsoft officially stopped backing up the system registry to the \Windows\System32\config\RegBack