AFE4900: Variable sized pads for 0.4 mm pitch BGAs like the AFE4900

Hi I am designing a product with the AFE4900 and other 0.4 mm pitch DSBGA packages (BQ25120A). These packages require a 0.23 mm pad, which is quite challenging for the PCB manufacturer if one wants to use a via-in-pad. I noticed in the design guide TIDA-01580 that Ti is using 0.23 mm NSMD pads for the outer pads. For the inner pads with vias Ti uses 10 mil NSMD pads (0.254 mm) with an 6 mil (0.1524 mm) drill. I just wanted to ask in which cases this is ok, becasue I could not confirm this in the documents "SPRAAV1C PCB Design Guidelines for 0.4mm Package-On-Package (PoP) Packages, Part I" or "SNVA009AI AN-1112 DSBGA Wafer Level Chip Scale Package".

Thanks in advance