Why D50DNP BMC report PCIe Correctable Link Speed Changed?

Why D50DNP BMC report PCIe Correctable Link Speed Changed?

From BMC warning information , the device is related to  M.2 device
As DNP TPS ,DNP support PCIe x4 Gen3 m.2 device  , BMC would report Link speed change if installed Gen4 M.2 device.

TPS Section 8.1