https://arstechnica.com/gadgets/2024/05/m4-ipad-pro-cpu-cores-and-ram-amount-are-tied-to-storage-capacity/

When Apple announced the Apple M4 chip during its iPad Pro event yesterday, it mentioned that the chip came with "up to" four high-performance CPU cores.

Those short, easily missable words always mean that there's a lower-end version of the chip coming that doesn't include that many CPU cores, and the tech specs page for the new iPad Pro has the full details: iPad Pros with 256GB or 512GB of storage use a version of the M4 with three high-performance CPU cores and six smaller efficiency cores. Only the models with 1TB and 2TB of storage have an M4 with all four high-performance CPU cores enabled.