Looks like the distance (as well as lap and average times) is read from GPS rather than the Foot Pod even when „Distance: Always” is set in the menus. This only affects Bluetooth foot pods, not ANT+ as well.
Take a look at these activities:
BT Calib. 50: https://connect.garmin.com/modern/activity/3414316342
BT Calib. 150: https://connect.garmin.com/modern/activity/3414324275
ANT+ Calib 150: https://connect.garmin.com/modern/activity/3414819619
I have ran a 200 m segment a few times at the same pace, deliberately changing the calibration factor from 50 to 150. Note, how the first two activities have the same distance and pace averages, despite the calib. factor.
Not the case when using the ANT+ FP (see activity 3), which seems to actually use the foot pod for distance.
Same happened with a friend's Fenix 5.
