Distance discrepancy - PC vs iOS companion

I did a 100km group ride today (PC app) but by the end it was showing 106.5km on the iOS companion app. The longer of the two distances uploaded to Strava. Has anyone experienced this before? Might be unrelated but I consistently averaged higher W/kg than others in the same ride and I’m wondering if there’s a link.

I would be interested to know more about this as well as I have a similar issue. When I completed stage 1 of the Tour de Zwift I found that often the people in the pack I was cycling with had covered much less distance. For example the timing board stated I completed 24.7km but the two individuals ahead of me with 0 time difference were at 24.1km.

In addition, even for routes I seem to always have a larger distance then what’s stated including adding extra for the lead-in. For Road to Sky when I reach the top it has me at 18.5km vs the stated 17.5km +0.1km lead in.

Any ideas on how to correct this would be appreciated.