As Tom's Hardware explains, it all comes down to 3D NAND selection. To saturate a PCIe 5.0 x4 drive (15.754 GBps in both directions), you need 3D NAND with a 2400 MTps interface. Micron was the first to announce this type of memory back in July. SK Hynix and YMTC...
https://www.techspot.com/news/95924-why-pcie-50-ssds-limited-10-gbps-while.html?utm_source=dlvr.it&utm_medium=blogger
https://www.techspot.com/news/95924-why-pcie-50-ssds-limited-10-gbps-while.html?utm_source=dlvr.it&utm_medium=blogger