Then why isn’t it Windows 10.1?................
Normally it should have been Windows 10 release 21H2, nothing more.
But Microsoft is breaking compatibility in a Big Way, and incompatible releases traditionally warrant a major version increment.
It appears to me that Windows 11 is unfortunately destined to be an "Every Other Release Is A Loser" release, like Win8, and Vista, and WinME.
In addition, Win11 is a "Hardware Vendors Full Sales Quota Act" release, just like Vista -- "Okay, everybody buy new computers!!" That's not a guaranteed win for anybody.