Running a checker downloaded from GitHub is incredibly risky. These repositories are frequently "backdoored," meaning the script steals the user's own data while it runs. For the Service (Netflix):
In 2019, a man named Moises Jose Molina Marquez was sentenced to 33 months in prison for running a site that sold access to hacked streaming accounts (Netflix, Hulu, etc.). He used a modified version of an open-source account checker. netflix account checker github link
While the technical curiosity behind a is understandable, the risks far outweigh the rewards. For aspiring developers, it is much safer—and more impressive to employers—to build automation tools for public APIs or open-source projects rather than venturing into the realm of account validation. The World of Open-Source Code Sharing: A Look into GitHub
Searching for the exact reveals several patterns: netflix account checker github link