This was my thought, too, especially with how stable Linux traffic is relative to other OSes.

It might just mean that more people are web scraping, and that web scraping is easier/cheaper on Linux.

The Steam numbers are more interesting to me, as a measure of consumer usage, since they should mostly represent people actually using their computer.

PornHUB puts out annual usage stats, too, but idk if they include OS. (When I used Reddit, their stats would come up on dataisbeautiful frequently enough to come to mind years later—they had some interesting stats, like average visit duration and that the most Republican states were the most likely to search for gay and incest porn, but I digress.). Would bots make up a high volume of traffic for them? I imagine not, since there's little economic value in scraping it (to train LLMs, in particular — I think it would poison the training data rather dramatically!)