It means they're going full remote. From the article linked in the comments:

> The company is also going fully remote, Dohmke wrote, telling staff they’re “seeing very low utilization rates” in their offices. “We are not vacating offices immediately, but will move to close all of our offices as their leases end or as we are operationally able to do so,” Dohmke wrote.

GitHub was already fully remote since forever, and long before Covid. The offices were just there as an option for employees who happened to live nearby, and for occasional, in-person meetings, but I doubt there was a single person who worked there full time. This isn't big news for the majority of GitHub employees.

It's always been fully remote