Originally Posted by
shelgame
For some reason, the iPhone GPS kept trying to 'snap' me to the nearby road(s).
It appears there might have been snapping going on but that's a secondary result of the inaccurate GPS positioning. That is, the GPS position drifted so that it appeared it was near the road and, then, the snapping occurred.
http://regex.info/blog/2015-12-03/2651
App developers can choose to record the uncorrected (no snapping) data.
But it seems that using other apps can enable it (it's a system-wide setting).