asus rog maximus z790 extreme

My copy of GPU-Z (version 2.51.0) reports Bus Interface as "PCIe 4.0 @ 8x." First my ASUS ROG Extreme Z790 has a PCIe 5.0 x16 Bus Interface and my RTX 4090 has a PCIe 4.0 x16 Bus Interface. Correct reporting should be PCIe 5.0 x8 which is equivalent to PCIe 4.0 x16 in bandwidth. Yesterday I...