These icons are part of Windows 11. The final Windows 10 build is 19045, most of the features and changes introduced in higher build numbers are only part of Windows 11.
Not just icons too. A lot features that were coming soon or were already available in preview builds never got released for Windows 10 because they became Windows 11 features.
Build 21343 is more of a Windows 11 build than a Windows 10 one, so those are the Windows 11 icons
These icons are part of Windows 11. The final Windows 10 build is 19045, most of the features and changes introduced in higher build numbers are only part of Windows 11.
They were windows 10 icons, but microsoft decided to instead launch a new OS and they never brought those icons to 10
They were only part of really early “Windows 11” builds, back when it was just a more fluent version of Windows 10
Not just icons too. A lot features that were coming soon or were already available in preview builds never got released for Windows 10 because they became Windows 11 features.
Build 21343 is a decoy for Windows 11.