Most compressed versions have the Windows Update service completely removed. This leaves your PC vulnerable to every new exploit discovered by hackers. Better Alternatives for Low-End PCs
These are well-known, community-vetted "de-bloated" versions of Windows. windows 10 pro highly compressed 18mb
A standard Windows 10 Pro ISO typically ranges from 4GB to 6GB. To reach 18MB, creators use extreme compression algorithms like KGB Archiver or 7-Zip with maximum dictionary sizes. Most compressed versions have the Windows Update service