fenix 6 pro run distance accuracy ??

anyone else having trouble with accuracy for Fenix 6 pro - it has been off from others around me using Garmin watches by as much as a mile plus less during a 1/2 marathon trail event - and almost 2 miles in a marathon i did recently - and yes is set for GPS + GLONASS - every second - etc - just about every run with it when I correct in strava it is adjusted - 

when I have ridden with it - it seems very close to my bike 520 plus - 

thoughts - ??