Why are badges getting retired? What is the upgrade about?

Khan Academy's infrastructural system is switching from an older language that cannot be supported as easily to Go, this requires a few sacrifices to allow for system efficiency.

Hopefully, those badges might return after the switch is complete. Otherwise, keep learning because there are other badges to achieve!

Let me know if I can do anything else for you!

To add on to what King said, this blog post goes into some detail about the "what"s and "why"s of the removal of the badges, as well as other parts of Khan, like the recent decision to remove the streaks feature. The short of it is that Khan Academy is slowly preparing to switch the code base that they use from Python 2 to Go, and this means removing (at least maybe temporarily) some of the features of Khan Academy that can take up a lot of data or time management for staff.