See, for example, this ride up the Col du Tourmalet: https://connect.garmin.com/modern/activity/1224308861.
With elevation corrections disabled, the elevation gain is shown as 1772m, which is pretty much spot-on: start at Saint-Savin at 550m, descend about 80m to Soulom, continuous climb to the summit at 2115m, descend back to Soulom, 80m climb back to Saint-Savin. However, if I enable elevation corrections, the elevation gain is shown as 3156m, which is about an 80% inflation over the real figure.
