The last firmware update for trackers such as the ...

The last firmware update for trackers such as the Charge 2 wasn't ready for release. It has messed up the distance tracking while connected to GPS. Fitbit is about 20% lower than the phone it's attached to.
The second major issue is the sleep tracking. It's right about 60% of the time. The remainder...it can split your sleep into sections with periods of unreported data.
Fitbit knows this, but has not provided their support staff with any knowledge as to when the next firmware release will be.
Rookies. Roll back to the prior release that worked, then roll out the fixed firmware.