I responded to a different comment but it's also relevant here.

You're hiring for a senior role, not a junior or mid.

Your candidates aren't fresh out of school or just starting their careers. They already have plenty of work experience. They already know how to code and have been doing it for years. A conversation will tell you much more about their approaches to problems solving, team work, and mentoring than a coding challenge will. Looking at their GitHub, their work experience and references will tell you the rest.

It's like asking a doctor to go over basic human anatomy.