Hi,
Some while ago i created a running segment. It was steep around 8 %. The GPS and the barometer showed similar data. The segment, however, shows 2 % climbing instead of 8 %. It seems segment uses the world map as elevation source which often is incorrect.
My suggestion would be that you can choose which data you want to create the segment based upon. Or, that the data is based on ”multi band” sources, using the average value of map+gps+barometer.