Without any data it is impossible to find out why the distances are short. Data that determines distance are club head speed / ball speed, vertical launch angle and spin. How are Your environmental settings?

Can you share the GPS track from that run? In my 10 year experience of running on trails, GPS watches tend to be short when running on trails due cutting through corners and switchbacks and straightening curves. I'd say, in my area getting the distances…

Here is a concrete example from a trail run today, and it didn't even have any switchbacks.

Fenix distance: 12.21 miles

Strava distance after distance correction: 12.89 miles, which means the original distance was more than 5% short.

Distance according…

My shots are coming up about 20 yards short as well. I haven’t compared side by side with another unit but play often on a trackman and have distances pretty dialed in. It is frustrating. 

I run many times with running partners who have non Vivoactive watches. I am off (shorted) a half mile for every 6 miles. Over a years running and that is some major missing mileage on my mileage goal 

I’m not thrilled so far. Broken out of the box and now distances are way short. I love being a beta tester 

This is currently being discussed in another thread:

forums.garmin.com/.../running-distance-usually-short

Hi, it's identified and should be fixed

https://forums.garmin.com/beta-program/fenix-7-series/f/announcements/408411/beta-version-21-05---check-for-updates-only

• Fixed distance short on walk activities with GPS