Microsoft ended support for pre-SP1 version of Windows 7 in April 2013 and then Service Pack 1 in January 2020. It also ended support for Windows 8.0 in 2016 and will end support for Windows 8.1 in 2023.
Then Microsoft ended support for version 1903 this month and older versions of Windows 10 Home and Pro. It also ended support for versions 1903 and 1709 and older of Windows Enterprise and Education, yet still supports 1803 and 1809 until May 2021. It also will end support for version 1507 of Windows 10 LTSC (more likely restricted to enterprises as it's not practical for home users and small businesses) in October 2025, ver 1607 LTSC in Oct 2026, and ver 1809 in January 2029.
Somehow, the chart data from analytics.wikimedia.org do not fully specify which unsupported and supported versions of Windows are used on desktop by Wikimedia users. Possibly, some of Windows 7 users still use pre-SP1 version, some of Windows 8 users still use version 8.0, and the share of Windows 10 may be fragmented.