Your situation is probably different from what we imagine. I ask you a few questions to help us resolve the issue quickly.
- Is the Board Support Package version 1.1.8 ?
- Is the “Adafruit SPIFlash” library version 4.3.4 ?
- What is the pin name (e.g. D2) used for wake-up? And what is connected to this pin?
- Please tell us everything that is connected to the XIAO pins without omitting anything. If possible, a connection diagram would be helpful.
- Please post your sketch.
The internal pull-up resistor of the nRF52840 is 15k. This means that about 31u-2.1u=29uA of current is passing through the pull-up resistor and out through the wake-up pin. Is something of about 3.3-29u*15k=2.9V connected to the wake-up pin?