Hi Adzah,
If the PC originally came with Windows 11 Home Single Language and it was changed to Windows 11 Pro, the Home Single Language digital license won't activate Pro. The installed edition needs to match the license.
Please check first:
Go to Settings → System → Activation and confirm it shows Windows 11 Pro.
If the original license is Home Single Language, the supported way to return to it is to back up your files and reinstall Windows 11 Home Single Language. Microsoft notes that changing from Pro back to an unsupported Home edition requires a clean installation.
Download the official Windows 11 installation media from Microsoft and create a bootable USB.
During Windows setup, select Windows 11 Home Single Language. If asked for a product key, select I don't have a product key.
Once installation is complete, connect to the internet and sign in with the Microsoft account linked to the original digital license. Windows should activate automatically if the license is tied to that device.
Important: Back up your important files before reinstalling, because a clean installation can remove the existing Windows installation and applications.
Thanks