I have an Intel i9 12900k which has 16 cores but my system recognizes two cpu with 8 cores each.
The I9-12900K has 8 performance cores (P cores) and 8 energy efficiency cores (E cores). Each core is designed differently to optimize for its goals, but supports the same software.
The overall goal is to have low power consumption on the E core, fast calculations on the P core, and a new operating system management control in Windows to make the CPU run most efficiently and also economically.
This system management control is fully enabled in Windows 11, while Windows 10 can achieve only some of the functions. In fact, this new hardware architecture is one of the main reasons for the existence of Windows 11.
As Windows 10 has only a partial understanding of this architecture, the CPU cores are divided into two groups by their differing characteristics. That's the way that the Windows 10 chipset driver has preferred to represent them to the Windows scheduler, which is just a compromise. The final effect for Windows as regarding the scheduling and execution of threads is exactly the same as for 16 separate cores.