For me, my exercise route GPS data from before my restore/iOS 14 is gone forever.
Follow these steps to export your Apple Health data and find out if yours is too.
1. Open Health App on iPhone
2. Click on your user icon in the top right
3. Scroll down and choose "Export All Health Data"
4. You can save it to iCloud or Airdrop directly to your computer
5. Once you copy over export.zip, extract it to get the apple_health_export folder.
6. Inside, you'll see a workout-routes folder. The .gpx files inside contain the GPS coordinates of your workout.
7. Open some of the files in a text editor. If it has GPS data, you will see a new line for every second of your workout. If the GPS data is missing, it will only show the time that you started the workout.