Max Speed Accuracy

I enjoy the Caynax Tracker but I need to know how you measure Max Speed.
On 3 occasions the Max Speed has been rather high.
Either I am stronger than I thought or the Max Speed is measured from picking up the phone and looking at it.
Is this possible?
My Max was 16kph, 20kph & 22kph.
I didn’t know I could Paddle that fast.

Average speed was about 10-12kph.

I can provide derailed history if needed.
Pls help.

Max speed is returned by GPS - not calculated by app. Unfortunately sometimes GPS reports wrong values and although we are trying to detect such anomalies we really don’t know whether you are actually going that fast right now.