If you look at page 1-8 of the manual it confirms this is the case. Ryzen Gen 1 & 2 will drop to PCIE Gen 3.0 (supported) on M2.2 Device which is the CPU direct (definable by the drop in GEN from 4 to 3), while the x570 chipset maintains PCIE Gen 4.0 regardless (M2.1 Device)
So unless a missprint this is confirmed and varies to say page 1-8 of CH8 Manual (which is the way we think it should be)
I would have thought the other way round as well (lucky you checked).