Valve has recently announced that Steam will stop supporting certain old Windows OS support next year.
It was officially revealed that Steam will stop its support for Windows 7 and Windows 8 starting January 1, 2024. It will specifically stop support for Windows 7, Windows 8, and Windows 8.1 systems. After that date, the Steam Client will stop running on those versions of Windows.
In order for players to run Steam and any games or other products purchased via Steam, they will have to update to a more recent version of Windows. In other words, the client will only run on Windows 10 and onwards.
There is actually a reason why Valve is abandoning support for older Windows OS. The newest features in Steam rely on an embedded version of Google Chrome, which no longer functions on older versions of Windows. So, Valve is forced to make this change so that the Steam client functions properly. It also revealed that future versions of the client will need Windows feature and security updates that are only available in Windows 10 and above.
Users who are still using Windows 7 and Windows 8 OS, they will now be forced to upgrade to Windows 10 at least.