Perfect example of Google maps issue, is that we did Grampians on the weekend here in Australia. And, it still had a road/track which had been completely deleted (probably long ago). And it wasn't on any other maps.. There was a rusted sign that had been long removed and sawed off sitting where the route clearly used to be, but no sign of route anymore

These days, most people tend to just use AllTrails or Avenza because they're convenient. For Thru hiking (really long hikes), people tend to use products (apparently) like Captopo which better facilitate planning, tagging on long hikes and time calculations (I am hoping to do a thru hike soon).

In practice though, stolen untested routes used in Alltrails present their own problems though, as, the Alltrails team don't actually check if the routes are safe or correct. I suspect they just steal them from other sources. But, for most people, its great as its convenient

OpenTopo/Openstreetmaps are commonly used as the source for a lot of mapping systems though, as it tends to be up to date and accurate in most places. (i use it on my garmin etrex 32x as a backup). I was also advised to use Strava Heatmaps on a hike I am planning to do to find water in certain locations, however, I use GPX Map viewer Pro, and use people I trust for routes if possible (or make my own).

Google Maps is great for roads, but, the data simply isn't that accurate for anything else. And, there is no good way to report bad hiking routes. With OSM and other things, they can be fairly easily fixed