Function of undocumented pads on PCB mount power module
My guess is they are pogo-pin-test-bench test points.

I'd be amazed if one of the "GND" ones isn't in some way Vout or related to it.

They use those to test the module in an automated jig to see if it works as intended, BUT...

You cannot use them reliably, because you have no knowledge of what they are connected to exactly. One may be connected to GND directly, or it may have a buffer component like a 1Ohm resistor for some unknowable reason.

I think it's a bit sloppy to put them so close to actual pads and not even mention a DNC notice on a few more pages, but, companies these days get to be a little sloppy some times.