Hi,
Many users have recently reported this issue, and based on feedback, the usual troubleshooting steps do not seem to resolve it.
Try:
System Recovery without deleting your files and apps.
Click the Start menu > Settings > System > Recovery.
Choose Reinstall Now under the section labeled 'Fix problems using Windows Update.'
Once completed, your system will restart. Switch out the S mode again.
If the issue persists, this looks like a temporary glitch on Microsoft’s side, possibly due to a high number of users trying to switch out of S Mode at the same time. In most cases, waiting 24–48 hours allows the system to stabilize and the issue to resolve automatically.
If the issue is urgent and you still cannot switch out of S Mode, the alternative option is to perform a clean installation of Windows. If you choose to proceed, please make sure to back up all your important files first before continuing.