So you got your hands on a so called leak from the shady parts of the internet and people want to make you believe it’s Windows 8.1 Update 3, Windows 9 or even Windows 11. This is how you find out your Build number and the official product name in seconds.
Finding out the full Windows Build Number
Do a search for ntoskrnl.exe and click on Open file location.
Right-click on ntoskrnl.exe and select Properties.
In Details you will find your full Window Build number.
Finding out your Windows Version, Name and Edition and the short Windows Build Number
Just run the command winver in the search.
A Window pops up with your Windows Build Number in short form and additional information about edition and version.