In almost every case, the so-called “50MB Windows 10” is one of the following:
Downloading "highly compressed" operating systems from unofficial sources carries significant risks: windows 10 highly compressed 50mb
An official, "debloated" version of Windows intended for enterprise and IoT devices (requires specific licensing). ChromeOS Flex: In almost every case, the so-called “50MB Windows
Downloading operating systems from unofficial, "highly compressed" sources carries extreme risks: Credential Theft In almost every case