Sure, it's only about half a percentage point. However, relatively speaking, the increase is rather significant at over 30%, also this being the first time Linux having a larger share than macOS.
My guess is that these are the Windows 7 holdouts who refuse to move to Win 10/11. Steam recently added a notification and countdown to Win 7 clients alerting the end of support for Steam on the OS.
Do you think people who still use Windows 7 now, 5 months before the deadline, switch to Linux instead of upgrading Windows?
I want to believe, but it seems unlikely to me. Sure, you'd need to pay me to use Windows 10 and 11, but they don't seem much worse than Windows 7 to me.