Our tracking code is installed on more than 1.5 million sites globally. These sites cover various activities and geographic locations. Every month, we record billions of page views to these sites.
They uses website trackers to compute the data, which is not a reliable way to count linux market share. A large percentage of linux user are privacy conscious, and tend to mess with tracking scripts.
Here are some potential inaccuracy in tracking:
Good amount of unknown is probably people with tracker blocker, which blocked part of their tracking scripts. Or send confusing information to the tracker.
There are probably some Linux Machine shows up as Windows machine, since many browser pretend to run on windows to avoid fingerprinting.
Finally, the linux number itself might be overblown, as many browser has randomized fingerprint to prevent tracking, making them being tracked as different user.
Also a lot of enterprise equipment runs on some kind of Linux and may also inflate the numbers. Linux will always be around, it's windows and Mac os that need their parent companies to survive