Is MS confused?
And no one said it's not supporting PCIe 4.0, because it needs to be slightly customized to run through 2x PCIe 4.0 lanes instead of naturally 4x lanes like all m.2 SSD's. This will ensure that you can't upgrade the internal storage cheaply as all of them are meant to run through 4x lanes.
The off the shelf one runs through 4x lanes:
- Read speeds up to 2,400 MB/s and low power consumption leverages both the PCIe Gen3 x4 interface, as well as sophisticated NVMe power management
The Western Digital PC SN530 NVMe™ SSD is designed for a multitude of applications that require both high performance and low power. The device is not only capable of more than three times the read speed over SATA SSDs, but further optimizes the low power consumption level to a mere 5mW...
www.westerndigital.com
My Samsung 970 Pro PCIe 3.0 can work natively on PCIe 4.0 motherboards. So the only customization done here is more like "castration". Now we understand why it's using 2x lanes, which was pretty weird to read in the hot chips.
Keep that crow in the fridge in the meanwhile.
EDIT:
Like PCIe 3.0, PCIe 4.0 is forward and backward compatible. This means that PCIe 4.0 can be used as a direct replacement for PCIe 3.0, but it also means that if you connect a PCIe 3.0 card to the PCIe 4.0 slot, the card will perform to the PCIe 3.0 specs.