If there are no connections on any pins or pads other than the 5V and GND pins connected to ppk2, it is strange that the sleep current is over 100uA.
It could be leakage current from C10 and C39, but I don’t know if 50uA is a reasonable value.
For reference, the sleep current is less than 50uA when powered from the battery pad as shown in the link below.