PCIe AC coupling capacitor size

The Design Guide specifies that the AC coupling capacitors for all PCIe interfaces should have a value of 0.22uF, but I noticed that the P3768 reference design uses 0.1uF capacitors for the PCIe#1 interface (M.2 WIFI/BT). Is that a mistake in the design, or do certain devices need to use 0.1uF capacitors?

Should 0.22uF be used on all the PCIe interfaces, or only on ones that will connect to Gen4 devices?