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Strava is an application that is a tracker gps for people that exercise. Strava allowed us to use their data.
This is their imagery:
tms[3,16]:https://proxy.nakarte.me/https/heatmap-external-b.strava.com/tiles-auth/all/red/{zoom}/{x}/{y}.png?px=256

Replace "all" with "ride" or "run" for more specific variants.

This also will show traces of some random tracks that sometimes should not be mapped so make sure you map the correct paths.