I posted the exact sketch I used to get the indicated output
Here is the setup information for my Sketch on Windows 10 using Arduino 1.8.16
I tacked small wires (30 gauge stranded) to the BAT and GND pads on the underside of the XIAO BLE Sense board and connected to a battery holder for my LiPo.
Of course I ran the sketch with no battery installed first, and saw “drifting” values for the ADC reading—all of them within the 10-bit range of the ADC. Then I installed the battery and got the measurements I showed.
Regards,
Dave