Wrong distance for route
I ride the same route twice a week, it's 68.5km. Strava records between 68.5 and 69km. Today, there was a road block, I had to take a detour for the last ten km. My Polar computer says I did 75.1km which I think is correct. it tells me an average speed of 29.9km/h. However, Strava says the route is 69.1km and average speed is 27.3km. Which is wrong.
Does Strava compare my trip to previous trips, and today did it decide there were errors in the gps and it "corrected" to what it thinks is the correct route?
This is today's ride: https://www.strava.com/activities/694506791
This is what I normally do: https://www.strava.com/activities/690702999